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 A333890 #4 Apr 09 2020 12:28:39 %S A333890 1,1,3,13,74,556,5369,64000,917235,15450781,300882997,6682784998, %T A333890 167423745058,4687321410460,145487540598936,4972006889998672, %U A333890 185965612590706251,7572297055379416985,334097417273761302271,15905277840810391655517,813931037149014145154401 %N A333890 Number of non-isomorphic n X n nonnegative integer symmetric matrices with all row and column sums equal to 5 up to permutations of rows and columns. %F A333890 The a(2) = 3 matrices are: %F A333890 [0 5] [1 4] [2 3] %F A333890 [5 0] [4 1] [3 2] %Y A333890 Column k=5 of A333737. %K A333890 nonn %O A333890 0,3 %A A333890 _Andrew Howroyd_, Apr 08 2020