%I #5 Apr 04 2020 19:03:44
%S 1,1,2,5,43,1856,1217727,8597641912,646296747486387,
%T 535435113671568180963,5081029530811947425598907884
%N Number of non-isomorphic n X n nonnegative integer matrices with all row and column sums equal to n up to permutations of rows and columns.
%e The a(2) = 2 matrices are:
%e [1 1] [2 0]
%e [1 1] [0 2]
%e .
%e The a(3) = 5 matrices are:
%e [1 1 1] [2 1 0] [2 1 0] [3 0 0] [3 0 0]
%e [1 1 1] [1 1 1] [0 2 1] [0 2 1] [0 3 0]
%e [1 1 1] [0 1 2] [1 0 2] [0 1 2] [0 0 3]
%Y Main diagonal of A333733.
%Y Cf. A110058.
%K nonn,more
%O 0,3
%A _Andrew Howroyd_, Apr 04 2020
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