A052281 - OEIS

%I #7 Jun 24 2020 12:04:05

%S 1,1,3,6,16,29,62,107,195,320,522,804,1234,1804,2626,3700,5155,7038

%N Number of 4 X 4 symmetric stochastic matrices under row and column permutations.

%C This sequence appears to be an erroneous version of A333886.

%e There are 6 nonisomorphic symmetric 4 X 4 matrices with row and column sums 3:

%e [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 [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 [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 [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 But, A333886 gives 6 other cases.

%Y Cf. A053493, A001496, A052280, A052282.

%K more,nonn,unkn

%O 0,3

%A _Vladeta Jovovic_, Feb 06 2000