A 4 x 4 Magic Square with Pairwise Relatively Prime Entries












7












$begingroup$


Find a 4 x 4 magic square of positive integers such that any two of its entries are pairwise different and relatively prime, i.e., have no common divisor greater than 1.



What is the least that the largest number in such a square can be?










share|improve this question











$endgroup$












  • $begingroup$
    What is “pairwise different”?
    $endgroup$
    – Arvasu Kulkarni
    11 hours ago










  • $begingroup$
    @ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
    $endgroup$
    – Bernardo Recamán Santos
    11 hours ago










  • $begingroup$
    Was this puzzle of your own creation?
    $endgroup$
    – Brandon_J
    5 hours ago










  • $begingroup$
    @Brandon_J: An oldie twisted.
    $endgroup$
    – Bernardo Recamán Santos
    4 hours ago










  • $begingroup$
    Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
    $endgroup$
    – kkm
    2 hours ago
















7












$begingroup$


Find a 4 x 4 magic square of positive integers such that any two of its entries are pairwise different and relatively prime, i.e., have no common divisor greater than 1.



What is the least that the largest number in such a square can be?










share|improve this question











$endgroup$












  • $begingroup$
    What is “pairwise different”?
    $endgroup$
    – Arvasu Kulkarni
    11 hours ago










  • $begingroup$
    @ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
    $endgroup$
    – Bernardo Recamán Santos
    11 hours ago










  • $begingroup$
    Was this puzzle of your own creation?
    $endgroup$
    – Brandon_J
    5 hours ago










  • $begingroup$
    @Brandon_J: An oldie twisted.
    $endgroup$
    – Bernardo Recamán Santos
    4 hours ago










  • $begingroup$
    Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
    $endgroup$
    – kkm
    2 hours ago














7












7








7


1



$begingroup$


Find a 4 x 4 magic square of positive integers such that any two of its entries are pairwise different and relatively prime, i.e., have no common divisor greater than 1.



What is the least that the largest number in such a square can be?










share|improve this question











$endgroup$




Find a 4 x 4 magic square of positive integers such that any two of its entries are pairwise different and relatively prime, i.e., have no common divisor greater than 1.



What is the least that the largest number in such a square can be?







mathematics computer-puzzle magic-square






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 4 hours ago









Jonathan Allan

17.8k14697




17.8k14697










asked 11 hours ago









Bernardo Recamán SantosBernardo Recamán Santos

2,4721343




2,4721343












  • $begingroup$
    What is “pairwise different”?
    $endgroup$
    – Arvasu Kulkarni
    11 hours ago










  • $begingroup$
    @ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
    $endgroup$
    – Bernardo Recamán Santos
    11 hours ago










  • $begingroup$
    Was this puzzle of your own creation?
    $endgroup$
    – Brandon_J
    5 hours ago










  • $begingroup$
    @Brandon_J: An oldie twisted.
    $endgroup$
    – Bernardo Recamán Santos
    4 hours ago










  • $begingroup$
    Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
    $endgroup$
    – kkm
    2 hours ago


















  • $begingroup$
    What is “pairwise different”?
    $endgroup$
    – Arvasu Kulkarni
    11 hours ago










  • $begingroup$
    @ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
    $endgroup$
    – Bernardo Recamán Santos
    11 hours ago










  • $begingroup$
    Was this puzzle of your own creation?
    $endgroup$
    – Brandon_J
    5 hours ago










  • $begingroup$
    @Brandon_J: An oldie twisted.
    $endgroup$
    – Bernardo Recamán Santos
    4 hours ago










  • $begingroup$
    Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
    $endgroup$
    – kkm
    2 hours ago
















$begingroup$
What is “pairwise different”?
$endgroup$
– Arvasu Kulkarni
11 hours ago




$begingroup$
What is “pairwise different”?
$endgroup$
– Arvasu Kulkarni
11 hours ago












$begingroup$
@ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
$endgroup$
– Bernardo Recamán Santos
11 hours ago




$begingroup$
@ArvasuKulkarni: Any two entries are different. They are also relatively prime, that is, they do not have a common divisor greater than 1.
$endgroup$
– Bernardo Recamán Santos
11 hours ago












$begingroup$
Was this puzzle of your own creation?
$endgroup$
– Brandon_J
5 hours ago




$begingroup$
Was this puzzle of your own creation?
$endgroup$
– Brandon_J
5 hours ago












$begingroup$
@Brandon_J: An oldie twisted.
$endgroup$
– Bernardo Recamán Santos
4 hours ago




$begingroup$
@Brandon_J: An oldie twisted.
$endgroup$
– Bernardo Recamán Santos
4 hours ago












$begingroup$
Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
$endgroup$
– kkm
2 hours ago




$begingroup$
Wow, that's the best puzzle I ever encountered here (and I've been a lurker for more than a year, I think). A question about the definition: can the square contain a 1, i. e. is 1 considered a coprime to any other natural number or not? It commonly is, but not always.
$endgroup$
– kkm
2 hours ago










3 Answers
3






active

oldest

votes


















3












$begingroup$

I believe this is optimal (unless I've missed a trick):





  1 13 47 53
29 59 7 19
41 11 37 25
43 31 23 17



Which has




a maximal value of 59 (and a sum of 114)


Note: all values are prime except for 1 and the composite number 25




I also found these two with the same maximum value:





  1 17 37 59
53 29 23 9
47 19 43 5
13 49 11 41
...using primes, 1, 9 and 49 (with a sum of 114);

and
  1 29 47 49
43 41 37 5
59 17 31 19
23 39 11 53
...using primes, 1, 39 and 49 (with a sum of 126)




First I found these two:





 1 11 41 61
47 31 17 19
43 13 53 5
23 59 3 29
and
 1 13 47 53
29 59 7 19
61 31 17 5
23 11 43 37
both of which have a maximal value of 61 (and a sum of 114)


For these I restricted myself to fifteen odd primes less than 73 and added the number one as the sixteenth value. These two have the smallest maximal value given this additional constraint.






share|improve this answer











$endgroup$













  • $begingroup$
    markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
    $endgroup$
    – Brandon_J
    4 hours ago










  • $begingroup$
    Ah, the diagonals. Thanks!
    $endgroup$
    – Brandon_J
    3 hours ago












  • $begingroup$
    The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
    $endgroup$
    – Jonathan Allan
    3 hours ago












  • $begingroup$
    Oh dang. Can I give you a +47 or so for finding this answer?
    $endgroup$
    – Brandon_J
    3 hours ago










  • $begingroup$
    Just found better :p
    $endgroup$
    – Jonathan Allan
    3 hours ago



















3












$begingroup$

I've got a solution:




and I admit I found it online.




Here it is:




Magic Square




The largest number in it is




73







share|improve this answer











$endgroup$













  • $begingroup$
    Maybe we can make a smaller one by using 1 as one of our numbers?
    $endgroup$
    – Jonathan Allan
    5 hours ago










  • $begingroup$
    I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
    $endgroup$
    – Brandon_J
    5 hours ago










  • $begingroup$
    I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
    $endgroup$
    – Jonathan Allan
    5 hours ago










  • $begingroup$
    @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
    $endgroup$
    – Brandon_J
    5 hours ago










  • $begingroup$
    1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
    $endgroup$
    – Jonathan Allan
    5 hours ago



















1












$begingroup$

The following magic square





 11  1 53 37
7 47 29 19
71 23 3 5
13 31 17 41



has magic constant




102




and largest number




71







share|improve this answer









$endgroup$













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    3 Answers
    3






    active

    oldest

    votes








    3 Answers
    3






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3












    $begingroup$

    I believe this is optimal (unless I've missed a trick):





      1 13 47 53
    29 59 7 19
    41 11 37 25
    43 31 23 17



    Which has




    a maximal value of 59 (and a sum of 114)


    Note: all values are prime except for 1 and the composite number 25




    I also found these two with the same maximum value:





      1 17 37 59
    53 29 23 9
    47 19 43 5
    13 49 11 41
    ...using primes, 1, 9 and 49 (with a sum of 114);

    and
      1 29 47 49
    43 41 37 5
    59 17 31 19
    23 39 11 53
    ...using primes, 1, 39 and 49 (with a sum of 126)




    First I found these two:





     1 11 41 61
    47 31 17 19
    43 13 53 5
    23 59 3 29
    and
     1 13 47 53
    29 59 7 19
    61 31 17 5
    23 11 43 37
    both of which have a maximal value of 61 (and a sum of 114)


    For these I restricted myself to fifteen odd primes less than 73 and added the number one as the sixteenth value. These two have the smallest maximal value given this additional constraint.






    share|improve this answer











    $endgroup$













    • $begingroup$
      markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
      $endgroup$
      – Brandon_J
      4 hours ago










    • $begingroup$
      Ah, the diagonals. Thanks!
      $endgroup$
      – Brandon_J
      3 hours ago












    • $begingroup$
      The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
      $endgroup$
      – Jonathan Allan
      3 hours ago












    • $begingroup$
      Oh dang. Can I give you a +47 or so for finding this answer?
      $endgroup$
      – Brandon_J
      3 hours ago










    • $begingroup$
      Just found better :p
      $endgroup$
      – Jonathan Allan
      3 hours ago
















    3












    $begingroup$

    I believe this is optimal (unless I've missed a trick):





      1 13 47 53
    29 59 7 19
    41 11 37 25
    43 31 23 17



    Which has




    a maximal value of 59 (and a sum of 114)


    Note: all values are prime except for 1 and the composite number 25




    I also found these two with the same maximum value:





      1 17 37 59
    53 29 23 9
    47 19 43 5
    13 49 11 41
    ...using primes, 1, 9 and 49 (with a sum of 114);

    and
      1 29 47 49
    43 41 37 5
    59 17 31 19
    23 39 11 53
    ...using primes, 1, 39 and 49 (with a sum of 126)




    First I found these two:





     1 11 41 61
    47 31 17 19
    43 13 53 5
    23 59 3 29
    and
     1 13 47 53
    29 59 7 19
    61 31 17 5
    23 11 43 37
    both of which have a maximal value of 61 (and a sum of 114)


    For these I restricted myself to fifteen odd primes less than 73 and added the number one as the sixteenth value. These two have the smallest maximal value given this additional constraint.






    share|improve this answer











    $endgroup$













    • $begingroup$
      markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
      $endgroup$
      – Brandon_J
      4 hours ago










    • $begingroup$
      Ah, the diagonals. Thanks!
      $endgroup$
      – Brandon_J
      3 hours ago












    • $begingroup$
      The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
      $endgroup$
      – Jonathan Allan
      3 hours ago












    • $begingroup$
      Oh dang. Can I give you a +47 or so for finding this answer?
      $endgroup$
      – Brandon_J
      3 hours ago










    • $begingroup$
      Just found better :p
      $endgroup$
      – Jonathan Allan
      3 hours ago














    3












    3








    3





    $begingroup$

    I believe this is optimal (unless I've missed a trick):





      1 13 47 53
    29 59 7 19
    41 11 37 25
    43 31 23 17



    Which has




    a maximal value of 59 (and a sum of 114)


    Note: all values are prime except for 1 and the composite number 25




    I also found these two with the same maximum value:





      1 17 37 59
    53 29 23 9
    47 19 43 5
    13 49 11 41
    ...using primes, 1, 9 and 49 (with a sum of 114);

    and
      1 29 47 49
    43 41 37 5
    59 17 31 19
    23 39 11 53
    ...using primes, 1, 39 and 49 (with a sum of 126)




    First I found these two:





     1 11 41 61
    47 31 17 19
    43 13 53 5
    23 59 3 29
    and
     1 13 47 53
    29 59 7 19
    61 31 17 5
    23 11 43 37
    both of which have a maximal value of 61 (and a sum of 114)


    For these I restricted myself to fifteen odd primes less than 73 and added the number one as the sixteenth value. These two have the smallest maximal value given this additional constraint.






    share|improve this answer











    $endgroup$



    I believe this is optimal (unless I've missed a trick):





      1 13 47 53
    29 59 7 19
    41 11 37 25
    43 31 23 17



    Which has




    a maximal value of 59 (and a sum of 114)


    Note: all values are prime except for 1 and the composite number 25




    I also found these two with the same maximum value:





      1 17 37 59
    53 29 23 9
    47 19 43 5
    13 49 11 41
    ...using primes, 1, 9 and 49 (with a sum of 114);

    and
      1 29 47 49
    43 41 37 5
    59 17 31 19
    23 39 11 53
    ...using primes, 1, 39 and 49 (with a sum of 126)




    First I found these two:





     1 11 41 61
    47 31 17 19
    43 13 53 5
    23 59 3 29
    and
     1 13 47 53
    29 59 7 19
    61 31 17 5
    23 11 43 37
    both of which have a maximal value of 61 (and a sum of 114)


    For these I restricted myself to fifteen odd primes less than 73 and added the number one as the sixteenth value. These two have the smallest maximal value given this additional constraint.







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited 2 hours ago

























    answered 4 hours ago









    Jonathan AllanJonathan Allan

    17.8k14697




    17.8k14697












    • $begingroup$
      markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
      $endgroup$
      – Brandon_J
      4 hours ago










    • $begingroup$
      Ah, the diagonals. Thanks!
      $endgroup$
      – Brandon_J
      3 hours ago












    • $begingroup$
      The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
      $endgroup$
      – Jonathan Allan
      3 hours ago












    • $begingroup$
      Oh dang. Can I give you a +47 or so for finding this answer?
      $endgroup$
      – Brandon_J
      3 hours ago










    • $begingroup$
      Just found better :p
      $endgroup$
      – Jonathan Allan
      3 hours ago


















    • $begingroup$
      markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
      $endgroup$
      – Brandon_J
      4 hours ago










    • $begingroup$
      Ah, the diagonals. Thanks!
      $endgroup$
      – Brandon_J
      3 hours ago












    • $begingroup$
      The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
      $endgroup$
      – Jonathan Allan
      3 hours ago












    • $begingroup$
      Oh dang. Can I give you a +47 or so for finding this answer?
      $endgroup$
      – Brandon_J
      3 hours ago










    • $begingroup$
      Just found better :p
      $endgroup$
      – Jonathan Allan
      3 hours ago
















    $begingroup$
    markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
    $endgroup$
    – Brandon_J
    4 hours ago




    $begingroup$
    markfarrar.co.uk/msq4x4cm.htm does not like your solution, but I can't find the error.
    $endgroup$
    – Brandon_J
    4 hours ago












    $begingroup$
    Ah, the diagonals. Thanks!
    $endgroup$
    – Brandon_J
    3 hours ago






    $begingroup$
    Ah, the diagonals. Thanks!
    $endgroup$
    – Brandon_J
    3 hours ago














    $begingroup$
    The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
    $endgroup$
    – Jonathan Allan
    3 hours ago






    $begingroup$
    The diagonals work, but not whatever else this considers when deciding if it is "perfect" - looking at the results when you give a magic total it seems to want squares and offset 2-by-1s or 1-by-2s and non-main diagonals.
    $endgroup$
    – Jonathan Allan
    3 hours ago














    $begingroup$
    Oh dang. Can I give you a +47 or so for finding this answer?
    $endgroup$
    – Brandon_J
    3 hours ago




    $begingroup$
    Oh dang. Can I give you a +47 or so for finding this answer?
    $endgroup$
    – Brandon_J
    3 hours ago












    $begingroup$
    Just found better :p
    $endgroup$
    – Jonathan Allan
    3 hours ago




    $begingroup$
    Just found better :p
    $endgroup$
    – Jonathan Allan
    3 hours ago











    3












    $begingroup$

    I've got a solution:




    and I admit I found it online.




    Here it is:




    Magic Square




    The largest number in it is




    73







    share|improve this answer











    $endgroup$













    • $begingroup$
      Maybe we can make a smaller one by using 1 as one of our numbers?
      $endgroup$
      – Jonathan Allan
      5 hours ago










    • $begingroup$
      I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
      $endgroup$
      – Brandon_J
      5 hours ago










    • $begingroup$
      I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
      $endgroup$
      – Jonathan Allan
      5 hours ago










    • $begingroup$
      @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
      $endgroup$
      – Brandon_J
      5 hours ago










    • $begingroup$
      1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
      $endgroup$
      – Jonathan Allan
      5 hours ago
















    3












    $begingroup$

    I've got a solution:




    and I admit I found it online.




    Here it is:




    Magic Square




    The largest number in it is




    73







    share|improve this answer











    $endgroup$













    • $begingroup$
      Maybe we can make a smaller one by using 1 as one of our numbers?
      $endgroup$
      – Jonathan Allan
      5 hours ago










    • $begingroup$
      I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
      $endgroup$
      – Brandon_J
      5 hours ago










    • $begingroup$
      I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
      $endgroup$
      – Jonathan Allan
      5 hours ago










    • $begingroup$
      @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
      $endgroup$
      – Brandon_J
      5 hours ago










    • $begingroup$
      1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
      $endgroup$
      – Jonathan Allan
      5 hours ago














    3












    3








    3





    $begingroup$

    I've got a solution:




    and I admit I found it online.




    Here it is:




    Magic Square




    The largest number in it is




    73







    share|improve this answer











    $endgroup$



    I've got a solution:




    and I admit I found it online.




    Here it is:




    Magic Square




    The largest number in it is




    73








    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited 5 hours ago

























    answered 5 hours ago









    Brandon_JBrandon_J

    1,423127




    1,423127












    • $begingroup$
      Maybe we can make a smaller one by using 1 as one of our numbers?
      $endgroup$
      – Jonathan Allan
      5 hours ago










    • $begingroup$
      I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
      $endgroup$
      – Brandon_J
      5 hours ago










    • $begingroup$
      I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
      $endgroup$
      – Jonathan Allan
      5 hours ago










    • $begingroup$
      @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
      $endgroup$
      – Brandon_J
      5 hours ago










    • $begingroup$
      1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
      $endgroup$
      – Jonathan Allan
      5 hours ago


















    • $begingroup$
      Maybe we can make a smaller one by using 1 as one of our numbers?
      $endgroup$
      – Jonathan Allan
      5 hours ago










    • $begingroup$
      I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
      $endgroup$
      – Brandon_J
      5 hours ago










    • $begingroup$
      I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
      $endgroup$
      – Jonathan Allan
      5 hours ago










    • $begingroup$
      @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
      $endgroup$
      – Brandon_J
      5 hours ago










    • $begingroup$
      1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
      $endgroup$
      – Jonathan Allan
      5 hours ago
















    $begingroup$
    Maybe we can make a smaller one by using 1 as one of our numbers?
    $endgroup$
    – Jonathan Allan
    5 hours ago




    $begingroup$
    Maybe we can make a smaller one by using 1 as one of our numbers?
    $endgroup$
    – Jonathan Allan
    5 hours ago












    $begingroup$
    I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
    $endgroup$
    – Brandon_J
    5 hours ago




    $begingroup$
    I'm not sure. I feel like I found a pretty reliable source @JonathanAllan
    $endgroup$
    – Brandon_J
    5 hours ago












    $begingroup$
    I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
    $endgroup$
    – Jonathan Allan
    5 hours ago




    $begingroup$
    I am not doubting Mathworld as a source, but did A. W. Johnson, Jr allow 1 or not?
    $endgroup$
    – Jonathan Allan
    5 hours ago












    $begingroup$
    @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
    $endgroup$
    – Brandon_J
    5 hours ago




    $begingroup$
    @JonathanAllan ah, I see what you mean. Does the OP allow the number one? I guess I should ask.
    $endgroup$
    – Brandon_J
    5 hours ago












    $begingroup$
    1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
    $endgroup$
    – Jonathan Allan
    5 hours ago




    $begingroup$
    1 is co-prime to all other integers. Note that I asked if we are only allowed positive integers because the same is true of -1.
    $endgroup$
    – Jonathan Allan
    5 hours ago











    1












    $begingroup$

    The following magic square





     11  1 53 37
    7 47 29 19
    71 23 3 5
    13 31 17 41



    has magic constant




    102




    and largest number




    71







    share|improve this answer









    $endgroup$


















      1












      $begingroup$

      The following magic square





       11  1 53 37
      7 47 29 19
      71 23 3 5
      13 31 17 41



      has magic constant




      102




      and largest number




      71







      share|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        The following magic square





         11  1 53 37
        7 47 29 19
        71 23 3 5
        13 31 17 41



        has magic constant




        102




        and largest number




        71







        share|improve this answer









        $endgroup$



        The following magic square





         11  1 53 37
        7 47 29 19
        71 23 3 5
        13 31 17 41



        has magic constant




        102




        and largest number




        71








        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 2 hours ago









        Freddy BarreraFreddy Barrera

        34318




        34318






























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