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 A052280 #9 Apr 04 2020 17:42:26 %S A052280 1,1,5,12,43,106,321,787,1960,4354,9386,18790,36362,66789,118936, %T A052280 203840,340195,551192,873343,1351457,2052221,3056798,4480565,6462678, %U A052280 9194098,12902867,17892986,24524478,33265476,44666016,59426834,78364873,102502765,133024660,171390035,219278224 %N A052280 Number of 4 X 4 stochastic matrices under row and column permutations. %e A052280 There are 5 nonisomorphic 4 X 4 matrices with row and column sums 2: %e A052280 [0 0 0 2] [0 0 0 2] [0 0 0 2] [0 0 1 1] [0 0 1 1] %e A052280 [0 0 2 0] [0 0 2 0] [0 1 1 0] [0 0 1 1] [0 1 0 1] %e A052280 [0 2 0 0] [1 1 0 0] [1 0 1 0] [1 1 0 0] [1 0 1 0] %e A052280 [2 0 0 0] [1 1 0 0] [1 1 0 0] [1 1 0 0] [1 1 0 0] %Y A052280 Row n=4 of A333733. %Y A052280 Cf. A001496, A052281, A052282. %K A052280 nonn %O A052280 0,3 %A A052280 _Vladeta Jovovic_, Feb 06 2000 %E A052280 Terms a(9) and beyond from _Andrew Howroyd_, Apr 04 2020