The contest

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  • #237
    Natalia Makarova
    Partecipante

    Dear Colleagues!

    I’ve decided to hold a contest on the issue pandiagonal squares of consecutive primes.
    I invite everyone to take part in solving this complex problem.

    Here is an article by my colleague Alex Chernov
    http://alex-black.ru/article.php?content=121

    In this article you will find a solution algorithm for n = 6.
    You can take this algorithm as a basis and make their changes to solve the problem.

    Many interesting ideas you can find in forum
    http://dxdy.ru/topic73817.html

    You can ask your questions here, and offer your ideas and algorithms.

    #238
    Natalia Makarova
    Partecipante

    For n = 7 we have a theoretical minimum magic constant S = 797.

    This square should be composed of the following array:

    7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 211 223 227 229 233 239

    I tried to make this square, I got a partial solution:

    I think that such a solution exists.

    #239
    Natalia Makarova
    Partecipante

    Let the scheme pandiagonal square of order 7 is this:

    a1 x1 a2 x2 a3 x3 a4
    x4 a5 x5 a6 x6 a7 x7
    a8 x8 a9 x9 a10 x10 a11
    x11 a12 x12 a13 x13 a14 x14
    a15 x15 a16 x16 a17 x17 a18
    x18 a19 x19 a20 x20 a21 x21
    x22 x23 x24 x25 x26 x27 x28

    Then the general formula pandiagonal square with magic constant S:

    x1 = -a11 + a12 + a13 + a15 + a16 + a17 + a20 + a21 - a4 + a5 + a6 + a8 + a9 – 2*S + x16 + x17 + x20 + x25 + x26 + x27,
    x2 = a12 - a18 - a4 + a5 + a8 + a9 - x16,
    x3 = a10 + a11 - a12 + a18 - a20 - a21 + a4 - a5 - a8 + S - x17 - x20 - x25 - x26 - x27,
    x4 = a10 + a12 + a13 + a16 + a19 + a9 - x16 - x17 - x20 - x25 - x27,
    x5 = a10 + a11 - a21 + a3 + a4 - a5 - x17,
    x6 = a13 + a14 + a16 + a17 + a18 + a20 + a21 - a3 - S + x16 + x17,
    x7 = -a10 - a11 - a16 - a18 + a21 - a4 + a5 + x17 + x20 + x25 + x27,
    x8 = -a10 - a12 - a13 - a16 - a17 - a19 - a20 - a21 - a5 - a8 - a9 + 2*S - x20 - x26,
    x9 = -a12 - a13 + a18 - a20 + a4 - a5 - a6 - a8 - a9 + S - x25,
    x10 = -a11 + 2*a12 + 2*a13 + a16 + a17 - a18 + a19 + 2*a20 + a21 - a4 + 2*a5 + a6 + a8 + a9 – 2*S + x20 + x25 + x26,
    x11 = -a11 + a13 + a16 + a17 + a19 + a20 + a21 - a3 + a5 - S + x16 + x17 + x20,
    x12 = a17 + a20 + a21 - a4 + a5 + a8 - S + x17 + x20 + x25 + x26,
    x13 = -a10 - a13 - a14 - a16 – 2*a17 - a18 - a20 - a21 + 2*S - x16 - x17 - x20 - x26,
    x14 = a10 + a11 - a12 - a13 + a18 - a19 - a20 - a21 + a3 + a4 - 2*a5 - a8 + S - x17 - x20 - x25,
    x15 = -a15 - a16 - a17 - a18 + S - x16 - x17,
    x18 = -a10 - a13 - a14 - a16 - a17 - a18 - a19 - a20 - a21 + a3 + S + x25 + x27,
    x19 = a10 + a12 + a13 + a14 + a15 + a16 + a17 + a18 + a6 + a9 - S - x20 - x25,
    x21 = -a12 - a15 - a3 - a6 - a9 + S - x27,
    x22 = a12 + a13 + a14 + a17 + a20 + a21 - a4 + a5 + a6 + a9 - S,
    x23 = a10 + a11 - a12 + a16 + a17 + a18 + a4 - a5 - a6 - x25 - x27,
    x24 = -a10 – 2*a12 – 2*a13 - a14 - a15 – 2*a16 – 2*a17 - a19 - 2*a20 - a21 + a4 - a5 - a6 - a8 – 2*a9 + 3*S - x26,
    x28 = -a11 + 2*a12 + a13 + a15 + a16 - a18 + a19 + a20 - a4 + a5 + a6 + a8 + a9 - S,
    a1 = a11 – 2*a12 – 2*a13 - a15 - a16 - a17 + a18 - a19 - a20 - a21 + a4 – 2*a5 - a6 - a8 – 2*a9 + 2*S,
    a2 = -a10 - a11 + a12 + a13 - a18 + a19 + a20 + a21 - a3 - a4 + a5,
    a7 = -a10 - a12 – 2*a13 - a14 - a16 - a17 - a19 - a20 - a21 - a5 - a6 - a9 + 2*S

    To construct a square about 7 pandiagonal of consecutive primes with a magic constant S = 797, you can use this pattern of residues modulo 4:

    1 3 1 3 3 3 3
    3 3 3 3 3 1 1
    1 1 1 1 3 3 3
    1 3 3 1 3 1 1
    3 3 1 1 1 3 1
    1 1 1 3 3 3 1
    3 3 3 1 1 3 3

    We have this pattern two groups of prime numbers:

    13  17  29  37  41  53  61  73  89  97  101  109  113  137  149  157  173  181  193  197  229  233 
    7  11  19  23  31  43  47  59  67  71  79  83  103  107  127  131  139  151  163  167  179  191  199  211  223  227  239 
    #240
    Natalia Makarova
    Partecipante

    Let pandiagonal square of order 8 is designated as follows:

    x1 x2 x3 x4 x5 x6 x7 x8
    x9 x10 x11 x12 x13 x14 x15 x16
    x17 x18 x19 x20 x21 x22 x23 x24
    x25 x26 x27 x28 x29 x30 x31 x32
    x33 x34 x35 x36 x37 x38 x39 x40
    x41 x42 x43 x44 x45 x46 x47 x48
    x49 x50 x51 x52 x53 x54 x55 x56
    x57 x58 x59 x60 x61 x62 x63 x64

    Then the general formula pandiagonal square with magic constant s has the form:

    x8=s-x1-x2-x3-x4-x5-x6-x7
    x16=s-x10-x11-x12-x13-x14-x15-x9
    x24=s-x17-x18-x19-x20-x21-x22-x23
    x32=s-x25-x26-x27-x28-x29-x30-x31
    x40=s-x33-x34-x35-x36-x37-x38-x39
    x42=-s-x1-x10+x12+x13+x14+x15-x17-x18-x2+x20+2x21+2x22+x23-x25-x26+x28+2x29+2x30+x31-x33-x34+x36+x37+x38+x39-x41-x9
    x43=4s+x1-x10-2x11-2x12-x13-x14-x15-x18-2x19-2x20-2x21-x22-x26-2x27-2x28-2x29-x3-x30-x34-2x35-2x36-x37-x38-x39+x41
    x44=s-x1+x14+x15-x17-x18-x19-x20-x25-x26-x27-x28+x38+x39-x4-x41
    x45=4s+x1-x11-2x12-2x13-2x14-x15+x17-x19-2x20-3x21-2x22-x23+x25-x27-2x28-3x29-2x30-x31-x35-2x36-2x37-2x38-x39+x41-x5
    x46=-s-x1+x11+x12+x18+x19+x20+x21+x26+x27+x28+x29+x35+x36-x41-x6
    x47=x1+x10-x14-x15+x17+x18+x19-x21-x22-x23+x25+x26+x27-x29-x30-x31+x33+x34-x38-x39+x41-x7+x9
    x48=-6s+x10+2x11+2x12+2x13+2x14+x15+x18+2x19+x2+3x20+3x21+2x22+x23+x26+2x27+3x28+3x29+x3+2x30+x31+x34+2x35+2x36+2x37+2x38+x39+x4-x41+x5+x6+x7
    x49=9s/2-x11-2x12-2x13-2x14-x15-x19-2x20-3x21-2x22-x23-x27-2x28-2x29-x3-2x30-x31-x35-x36-x37-x38-x39-x4-x5-x6-x7
    x50=-s/2+x1+x10+x11-x13-x14-x15+x17+x18+x19+x2-x21-2x22-x23+x25+x26+x27-x29+x3-x30-x31+x33+x34+x35+x9
    x51=-7s/2+2x10+2x11+2x12+x13+x17+2x18+2x19+x2+2x20+x21-x23+x25+2x26+2x27+2x28+x29+x3+x34+x35+x36+x4+x9
    x52=-9s/2+x10+2x11+2x12+2x13+x14+x17+2x18+3x19+3x20+3x21+2x22+x23+x26+2x27+2x28+2x29+x3+x30+x35+x36+x37+x4+x5
    x53=-7s/2+x11+2x12+2x13+2x14+x15-x17+x19+2x20+2x21+2x22+x23+x27+2x28+2x29+2x30+x31+x36+x37+x38+x4+x5+x6
    x54=-s/2-x10-x11+x13+x14+x15-x17-2x18-x19+x21+x22+x23-x25-x26-x27+x29+x30+x31+x37+x38+x39+x5+x6+x7-x9
    x55=9s/2-x1-2x10-2x11-2x12-x13-x17-2x18-3x19-x2-2x20-x21-x25-2x26-2x27-2x28-x29-x3-x33-x34-x35-x36-x37-x4-x5-x9
    x56=9s/2-x10-2x11-2x12-2x13-x14-x18-2x19-x2-3x20-2x21-x22-x26-2x27-2x28-2x29-x3-x30-x34-x35-x36-x37-x38-x4-x5-x6
    x57=-7s/2-x1+x11+2x12+2x13+2x14+x15-x17+x19+2x20+3x21+2x22+x23-x25+x27+2x28+2x29+x3+2x30+x31-x33+x35+x36+x37+x38+x39+x4-x41+x5+x6+x7-x9
    x58=5s/2-x10-x11-x12-x18-x19-x2-x20-x21-x26-x27-x28-x29-x3-x30-x34-x35-x36-x37-x38-x39+x41
    x59=s/2-x1-x10-x11+x14+x15-x17-x18-x19-x2+x21+x22+x23-x25-x26-x27+x29-x3+x30+x36+x37+x38+x39-x4-x41-x9
    x60=9s/2+x1-x10-2x11-3x12-2x13-2x14-x15-x18-2x19-3x20-3x21-2x22-x23+x25-x27-2x28-2x29-x3-x30-x35-2x36-x37-x38-x39-x4+x41-x5
    x61=s/2-x1-x13-x25+x35+x36+x38+x39-x4-x41-x5-x6
    x62=5s/2+x1+x10-x12-x13-2x14-x15+x17+x18-x20-2x21-2x22-x23+x25-x28-2x29-2x30-x31-x35-x36-x37-2x38-x39+x41-x5-x6-x7+x9
    x63=-7s/2+x10+2x11+2x12+x13+x14+x18+2x19+x2+2x20+2x21+x22+x26+x27+2x28+2x29+x3+x30+x35+x36+x37+x38+x4-x41+x5
    x64=-5s/2+x1+x10+x11+x12+x13+x17+x18+x19+x2+x20+x25+x26+x27+x3+x33+x34+x4+x41+x5+x6+x9

    See
    http://dxdy.ru/post906522.html#p906522

    This is a potential array of 64 consecutive prime numbers with a minimal of magic constant S = 2016:

    79  83  89  97  101  103  107  109  113  127  131  137  139  149  151  157  163  167  173  179  181  191  193  197  199  
    211  223  227  229  233  239  241  251  257  263  269  271  277  281  283  293  307  311  313  317  331  337  347  349  
    353  359  367  373  379  383  389  397  401  409  419  421  431  433  439

    You can use the pattern of residues modulo 4:

    3  1  3  1  1  3  1  3 
    3  1  3  3  3  3  3  1 
    1  1  1  3  1  1  1  3 
    3  1  1  3  3  1  1  3 
    1  1  1  3  1  3  3  3 
    1  1  3  1  1  1  1  3 
    3  3  1  1  3  1  3  1 
    1  3  3  1  3  3  3  3

    My solution with 14 errors:

    79 173 283 313 421 107 389 251
    167 277 311 419 103 383 199 157
    409 89 373 227 229 233 109 347
    331 349 197 139 211 293 137 359
    97 317 101 239 337 439 223 263
    401 181 127 353 269 281 241 163
    191 415* 473* 333* 191* 213* 127* 73*
    341* 215* 151 -7* 255* 67* 591* 403*
    S=2016

    This is a bad solution.

    Suggest your ideas, colleagues!

    #241
    Natalia Makarova
    Partecipante

    Denote pandiagonal square of order 6 as follows:

    a1 a2 a3 b1 b2 b3
    a4 a5 a6 b4 b5 b6
    a7 a8 a9 b7 b8 b9
    b1’ b2’ b3’ a1’ a2’ a3’
    b4’ b5’ b6’ a4’ a5’ a6’
    b7’ b8’ b9’ a7’ a8’ a9’

    Let the magic constant of this square is S.
    Denote: q = S/3.

    Theorem (author S. Belyaev)

    ai + ai’ – q = pi
    bi + bi’ – q = -pi

    (i = 1, 2, 3, …, 9)

    where

    p1 + p5 + p9 = 0
    p3 + p5 + p7 = 0
    p1 – p6 – p8 = 0
    p9 – p2 – p4 = 0
    p3 – p4 – p8 = 0
    p7 – p2 – p6 = 0

    so that the square:

    p1 p2 p3 -p1 -p2 -p3
    p4 p5 p6 -p4 -p5 -p6
    p7 p8 p9 -p7 -p8 -p9
    -p1 -p2 -p3 p1 p2 p3
    -p4 -p5 -p6 p4 p5 p6
    -p7 -p8 -p9 p7 p8 p9

    is pandiagonal square with magic constant S = 0.

    Example

    67 193 71 251 109 239
    139 233 113 181 157 107
    241 97 191 89 163 149
    73 167 131 229 151 179
    199 103 227 101 127 173
    211 137 197 79 223 83

    We have in this pandiagonal square:

    S = 930, q = 310

    p1 = -14
    p2 = 34
    p3 = -60
    p4 = -70
    p5 = 50
    p6 = -24
    p7 = 10
    p8 = 10
    p9 = -36

    More see here
    http://www.natalimak1.narod.ru/pannetr1.htm

    #243
    Natalia Makarova
    Partecipante

    Interesting conversion pandiagonal squares of order 7

    Let there pandiagonal square with magic constant S.

    also have pandiagonal square with magic constant S.

    Example

    S = 1597, z = 12

    #245
    Natalia Makarova
    Partecipante

    Suppose we are given an array of 49 numbers:

    7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 211 223 227 229 233 239

    Denote
    S1 – the sum of all the numbers array
    S = S1/7

    Definition 1

    Exact-square representation of an array as a series of magical rows is the following matrix 7×7, composed of 7 magic strings so that:
    1. is contained in a matrix each number of array only once;
    2. any two rows of the matrix does not contain the same numbers.

    Example 1

     7  29  89  107  157  181  227
    11  67  79   97  139  193  211
    13  41  53  149  163  179  199
    17  37  73  113  127  191  239
    19  47  59  131  151  167  223
    23  43  61  103  137  197  233
    31  71  83  101  109  173  229

    Definition 2

    Two exact-square representations of an array are called orthogonal if each row of the first representation has exactly one element in common with each row in the second representation.

    Example 2

     7  29  89  107  157  181  227
    11  67  79   97  139  193  211
    13  41  53  149  163  179  199
    17  37  73  113  127  191  239
    19  47  59  131  151  167  223
    23  43  61  103  137  197  233
    31  71  83  101  109  173  229
    
     7   43  97  109  151  191  199
    11  23  71  107  167  179  239
    13  59  73  103  139  181  229
    17  53  67    83  157  197  223
    19  79  89  101  127  149  233
    29  37  47  137  163  173  211
    31  41  61  113  131  193  227

    Theorem 1

    Two orthogonal exact-square representations of an array give semi-magic square with magic constant S, consisting of the numbers of the array.

    Example 3
    using two orthogonal exact-square representations of an array of Example 2

      7  29  89 107 157 181 227
     43 137 233  23 197 103  61
     97 211  79  11  67 139 193
    109 173 101  71  83 229  31
    151  47  19 167 223  59 131
    191  37 127 239  17  73 113
    199 163 149 179  53  13  41

    To be continued.

    #248
    Natalia Makarova
    Partecipante

    Theorem 2

    If

    a11 a12 a13 a14 a15 a16 a17
    a21 a22 a23 a24 a25 a26 a27
    a31 a32 a33 a34 a35 a36 a37
    a41 a42 a43 a44 a45 a46 a47
    a51 a52 a53 a54 a55 a56 a57
    a61 a62 a63 a64 a65 a66 a67
    a71 a72 a73 a74 a75 a76 a77

    is pandiagonal square of order 7 of different numbers, then there are four mutually orthogonal exact-square representations of an array of numbers that make up this square:

    #1
    a11 a12 a13 a14 a15 a16 a17
    a21 a22 a23 a24 a25 a26 a27
    a31 a32 a33 a34 a35 a36 a37
    a41 a42 a43 a44 a45 a46 a47
    a51 a52 a53 a54 a55 a56 a57
    a61 a62 a63 a64 a65 a66 a67
    a71 a72 a73 a74 a75 a76 a77
    
    #2
    a11 a21 a31 a41 a51 a61 a71
    a12 a22 a32 a42 a52 a62 a72
    a13 a23 a33 a43 a53 a63 a73
    a14 a23 a34 a44 a54 a64 a74
    a15 a25 a35 a45 a55 a65 a73
    a16 a26 a36 a46 a56 a66 a76
    a17 a27 a37 a47 a57 a67 a77
    
    #3
    a11 a22 a33 a44 a55 a66 a77
    a12 a23 a34 a45 a56 a67 a71
    a13 a24 a35 a46 a57 a61 a72
    a14 a25 a36 a47 a51 a62 a73
    a15 a26 a37 a41 a52 a63 a74
    a16 a27 a31 a42 a53 a64 a75
    a17 a21 a32 a43 a54 a65 a76
    
    #4
    a17 a26 a35 a44 a53 a62 a71
    a16 a25 a34 a43 a52 a61 a77
    a15 a24 a33 a42 a51 a67 a76
    a14 a23 a32 a41 a57 a66 a75
    a13 a22 a31 a47 a56 a65 a74
    a12 a21 a37 a46 a55 a64 a73
    a11 a27 a36 a45 a54 a63 a72

    The converse theorem is not true.

    Example
    this pandiagonal square 7th order of prime numbers with the magic constant S = 1597:

    191  89  397 409 43 157 311
    379 103 101 491  17 313 193
    317 241 109 163 439  47 281
    223 383 227 107 541  37  79
    331 337   7 139 167 563  53
     83 347 389 277 127 307  67
     73  97 367  11 263 173 613

    This square is made up of numbers of the following array:

    7 11 17 37 43 47 53 67 73 79 83 89 97 101 103 107 109 127 139 157 163 167 173 191 193 223 227 241 263 277 281 307 311 313 317 331 337 347 367 379 383 389 397 409 439 491 541 563 613

    We have four mutually orthogonal exact-square representations of an array:

    #1
    191 89  397 409  43 157 311
    379 103 101 491  17 313 193
    317 241 109 163 439  47 281
    223 383 227 107 541  37  79
    331 337   7 139 167 563  53
    83  347 389 277 127 307  67
    73   97 367  11 263 173 613
    
    #2
    191 379 317 223 331  83  73
     89 103 241 383 337 347  97
    397 101 109 227   7 389 367
    409 491 163 107 139 277  11
     43  17 439 541 167 127 263
    157 313  47  37 563 307 173
    311 193 281  79  53  67 613
    
    #3
    191 103 109 107 167 307 613
     89 101 163 541 563  67  73
    397 491 439  37  53  83  97
    409  17  47  79 331 347 367
     43 313 281 223 337 389  11
    157 193 317 383   7 277 263
    311 379 241 227 139 127 173
    
    #4
    311 313 439 107   7 347  73
    157  17 163 227 337  83 613
     43 491 109 383 331  67 173
    409 101 241 223  53 307 263
    397 103 317  79 563 127  11
     89 379 281  37 167 277 367
    191 193  47 541 139 389  97
    #249
    Natalia Makarova
    Partecipante

    My program has found a solution n = 7, S = 797 with 5 errors:

    131 137 223  149  11  139   7
     67  13  97  173  57* 233 157
    163 167  83  179  17   37 151
     73 109 117* 127 181* 101  89
    191  71  43   31 227   53 181
     41 239 199   79 197   23  19
    131* 61  35*  59 107  211 193

    I think there is a right solution.

    #250
    Natalia Makarova
    Partecipante

    My program has found a solution with 4 errors:

    151 139 227 181  13   79    7
     43  11  73 157  49* 253* 211
    167 137  97 193  23   31  149
    107 109 131 113 199   97*  41
    173 101  59  17 197   71  179
     53 239 127  89 233   37   19
    103  61  83* 47  83  229  191

    This I do a better approximation to the pandiagonal square of order 7 of consecutive primes with a magic constant S = 797.

    Does anybody have a better approximation?

    #253
    Natalia Makarova
    Partecipante

    Interesting conversion pandiagonal squares of order 7

    Let there pandiagonal square with magic constant S.

    also have pandiagonal square with magic constant S.

    Example
    S = 1597, z = 10

    7  139 167 563 53  331 337
    389 277 127 307 67  83  347
    367 11  263 173 613 73  97
    397 409 43  157 311 191 89
    101 491 17  313 193 379 103
    109 163 439 47  281 317 241
    227 107 541 37  79  223 383

    After the conversion

    7   129 177 563 53  331 337
    399 277 117 307 67  83  347
    357 21  263 173 613 73  97
    397 409 43  157 311 191 89
    101 491 17  313 193 389 93
    109 163 439 47  271 317 251
    227 107 541 37  89  213 383
    #254
    Natalia Makarova
    Partecipante

    I’m trying to make pandiagonal square of order 8 of the following consecutive primes:

    79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 211 223 227 229 233 239 241 251 257 263 269 271 277 281 283 293 307 311 313 317 331 337 347 349 353 359 367 373 379 383 389 397 401 409 419 421 431 433 439

    Magic constant S = 2016.

    I use a template from the residues modulo 4:

    1  3  3  3  3  1  3  3 
    1  3  3  1  3  3  3  3 
    3  1  1  3  1  3  3  1 
    3  1  3  3  1  1  1  3 
    1  1  3  1  3  3  3  1 
    3  1  1  3  1  1  1  1 
    1  1  1  1  3  3  3  3 
    3  1  1  1  1  1  3  1

    My program has found a solution with 11 errors:

    89   103  139  179  263  373 431  439
    313  271  359  389  151  131 191  211
    383  337  349  307  197  167 163  113
    227  269  107  127  353  409 241  283
    229  193  83   149  379  419 331  233
    367  433  293  347  137  181 101  157
    257  273* 281  285* 195* 239 263* 223
    151* 137* 405* 233* 341* 97  295* 357*

    The bad elements are marked *

    I think that can find the best solution.
    My computer runs very slowly.

    #256
    Natalia Makarova
    Partecipante

    This my pandiagonal square of order 8 of primes with magic constant
    S = 2000:

    11  13  683 293 647 263 59  31
    311 557 61  191 53  149 229 449
    29  233 193 443 197 353 163 389
    653 173 83  73  107 211 569 131
    23  67  641 269 659 317 17  7
    277 521 71  251 19  113 239 509
    103 347 167 281 271 467 137 227
    593 89  101 199 47  127 587 257

    Enlarge all elements of the square by 2, we obtain pandiagonal square of arbitrary natural numbers with magic constant S = 2016:

    13  15  685 295 649 265 61  33
    313 559 63  193 55  151 231 451
    31  235 195 445 199 355 165 391
    655 175 85  75  109 213 571 133
    25  69  643 271 661 319 19  9
    279 523 73  253 21  115 241 511
    105 349 169 283 273 469 139 229
    595 91  103 201 49  129 589 259

    On this square, I got a template (see above).
    We have a very similar pandiagonal square – a prototype of the desired solution.

    I have another prototype:

    63  117 171 225 279 333 387 441
    339 297 423 381 123 81  207 165
    405 351 321 267 237 183 153 99
    201 243 93  135 369 411 261 303
    219 177 111 69  435 393 327 285
    375 429 291 345 159 213 75  129
    273 315 357 399 105 147 189 231
    141 87  249 195 309 255 417 363

    S=2016

    This pandiagonal square of arbitrary natural numbers, but it gives us an idea about the structure of the desired solution.
    I take into account in its program structure representation – a sample. It helped me to find the best approximation to the solution.

    #257
    Natalia Makarova
    Partecipante

    My program has found a solution with 10 errors:

    89  83   151  223  227  373  431  439
    337 283  419  397  107  127  179  167
    367 353  313  251  257  199  163  113
    191 269  139  131  349  389  241  307
    233 193  103  137  379  383  311  277
    359 421  197  331  157  281  97   173
    229 305* 389* 397* 167* 83*  223* 223*
    211 109  305* 149  373* 181  371* 317

    Bad elements are marked *

    This pandiagonal square of order 8 with magic constant S = 2016, in there are only three non-prime numbers (305, 305, 371).
    But there is the same prime numbers (389, 397, 167, 83, 223, 373).

    #258
    Natalia Makarova
    Partecipante

    I changed the algorithm.
    Now my program has found a solution with 6 errors:

    79   401  107  89   383 397 367 193
    307  157  239  433  227 173 131 349
    313  167  389  151  181 263 241 311
    409  211  233  347  317 103 229 167*
    127  101  179  269  431 97  439 373
    271  337  331  197  191 353 223 113
    281  283  257  199  149 379 109 359
    229* 359* 281* 331* 137 251 277 151*

    This pandiagonal square of order 8 of consecutive primes with magic constant
    S = 2016.
    This solution is made only of primes, but there are the same numbers (167, 229, 359, 281, 331, 151).
    I got a good approximation to the solution.
    I think that you can find the best solution.

    Engaged someone with this problem? Please inform your preliminary results.

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