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 A052281 #7 Jun 24 2020 12:04:05 %S A052281 1,1,3,6,16,29,62,107,195,320,522,804,1234,1804,2626,3700,5155,7038 %N A052281 Number of 4 X 4 symmetric stochastic matrices under row and column permutations. %C A052281 This sequence appears to be an erroneous version of A333886. %e A052281 There are 6 nonisomorphic symmetric 4 X 4 matrices with row and column sums 3: %e A052281 [0 0 0 3] [0 0 1 2] [0 0 1 2] [0 0 1 2] [0 0 1 2] [0 1 1 1] %e A052281 [0 0 3 0] [0 0 2 1] [0 1 1 1] [0 1 2 0] [0 2 1 0] [1 0 1 1] %e A052281 [0 3 0 0] [1 2 0 0] [1 1 1 0] [1 2 0 0] [1 1 0 1] [1 1 0 1] %e A052281 [3 0 0 0] [2 1 0 0] [2 1 0 0] [2 0 0 1] [2 0 1 0] [1 1 1 0] %e A052281 But, A333886 gives 6 other cases. %Y A052281 Cf. A053493, A001496, A052280, A052282. %K A052281 more,nonn,unkn %O A052281 0,3 %A A052281 _Vladeta Jovovic_, Feb 06 2000