%I #5 Apr 06 2020 18:21:44

%S 1,2,3,4,6,8,18,40,230,4296,431206,162267272,201636689772,

%T 777816803942188,9865957936943931980,395886667549681689592056,

%U 53716176608076643470621240097,23524515269630339982914646822137232,35682168849414944013547274452501783251521

%N Number of non-isomorphic n X n binary matrices with equal row and column sums up to permutation of rows and columns and transposition.

%C Number of simple regular bicolored graphs on 2n unlabeled nodes and allowing the color classes to be interchanged.

%C First differs from A008324 at n=12. See the note in A004066 by Sean A. Irvine for an explanation of why these two sequences are different.

%F a(n) = (A333160(n) + A333681(n)) / 2.

%F a(n) >= A008324(n).

%Y Cf. A004066, A008324, A333160, A333681.

%K nonn

%O 0,2

%A _Andrew Howroyd_, Apr 03 2020