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 A333738 #5 Apr 09 2020 12:29:04 %S A333738 1,1,2,5,33,556,31781,5882230,3589936407,7347418294141, %T A333738 51304793433150418,1240428029662246026001,105148289475978338858008298, %U A333738 31582581551955332317665959184087 %N A333738 Number of non-isomorphic n X n nonnegative integer symmetric matrices with all row and column sums equal to n up to permutations of rows and columns. %e A333738 The a(3) = 5 matrices are: %e A333738 [0, 0, 3] [0, 1, 2] [0, 1, 2] [1, 0, 2] [1, 1, 1] %e A333738 [0, 3, 0] [1, 1, 1] [1, 2, 0] [0, 3, 0] [1, 1, 1] %e A333738 [3, 0, 0] [2, 1, 0] [2, 0, 1] [2, 0, 1] [1, 1, 1] %Y A333738 Main diagonal of A333737. %K A333738 nonn,more %O A333738 0,3 %A A333738 _Andrew Howroyd_, Apr 08 2020