This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A239671 #46 Sep 24 2015 05:00:51 %S A239671 3309,4659,5091,5433,7179,7431,7773,7863,8223,8367,8403,9501,9543, %T A239671 9573,9987,10029,10113,10371,10551,10821 %N A239671 Magic constants of the magic cubes 3 X 3 X 3 composed of prime numbers. %C A239671 A magic cube is the 3-dimensional equivalent of a magic square, that is, n^3 distinct integers arranged in an n X n X n grid such that the sum of the integers in each row, each column, each pillar, and the four main space diagonals is equal to the same number, called magic constant of the cube. %C A239671 The magic cube is associative if the sum of any 2 numbers, symmetrically located relative to the center of the cube, is equal to the same number, called constant of associativity of the cube. %C A239671 Magic cubes of order 3 are simple magic cubes. %C A239671 All magic cubes of order 3 are associative. %C A239671 The first two prime magic cubes of order 3 were found by Akio Suzuki in 1977 (see Prime Number Magic Cubes link). %C A239671 The general formula of the magic cube of order 3: %C A239671 ...................................................... %C A239671 . x1, x2, 3k/2-x1-x2, %C A239671 . x3, x4, 3k/2-x3-x4, %C A239671 . 3k/2-x1-x3, 3k/2-x2-x4, -3k/2+x1+x2+x3+x4, %C A239671 ....................................................... %C A239671 . -k+x2+x3+x4, 2k-2*x2-x4, k/2+x2-x3, %C A239671 . 2k-2*x3-x4, k/2, -k+2*x3+x4, %C A239671 . k/2-x2+x3, -k+2*x2+x4, 2k-x2-x3-x4, %C A239671 ....................................................... %C A239671 . 5k/2-x1-x2-x3-x4, -k/2+x2+x4, -k/2+x1+x3, %C A239671 . -k/2+x3+x4, k-x4, k-x3, %C A239671 . -k/2+x1+x2, k-x2, k-x1 %C A239671 ........................................................ %C A239671 Here k is the constant of associativity (any even number), x1, x2, x3, x4 are any integers. %H A239671 Harvey Heinz, <a href="http://www.magic-squares.net/c-t-htm/c_prime.htm">Prime Number Magic Cubes</a> %H A239671 Natalia Makarova, <a href="http://dxdy.ru/post818130.html#p818130">Discussion on scientific forum (in Russian)</a> %H A239671 Wikipedia, <a href="http://en.wikipedia.org/wiki/Magic_cube">Magic cube</a> %e A239671 For n = 3, a(3) = 5091. %e A239671 ...................... %e A239671 . 1061 3167 863 %e A239671 . 2243 431 2417 %e A239671 . 1787 1493 1811 %e A239671 ...................... %e A239671 . 2447 23 2621 %e A239671 . 1871 1697 1523 %e A239671 . 773 3371 947 %e A239671 ...................... %e A239671 . 1583 1901 1607 %e A239671 . 977 2963 1151 %e A239671 . 2531 227 2333 %e A239671 ...................... %K A239671 nonn %O A239671 1,1 %A A239671 _Natalia Makarova_, Mar 23 2014