%I #3 Dec 18 2015 18:17:26
%S 1,3,10,121,3680,326650,91271990,74872992399,208579984612008,
%T 1748923742658486631
%N Number of n X n binary matrices with floor(n^2/2) 1's and rows and columns in lexicographically nondecreasing order
%C Diagonal of A180979
%e All solutions for 3X3
%e ..0..0..0....0..0..0....0..0..0....0..0..1....0..0..1....0..0..1....0..0..1
%e ..0..1..1....0..0..1....0..1..1....0..1..0....0..0..1....0..1..0....0..1..0
%e ..0..1..1....1..1..1....1..0..1....0..1..1....0..1..1....1..1..0....1..0..1
%e ...
%e ..0..0..1....0..0..1....0..1..1
%e ..0..0..1....0..1..1....1..0..0
%e ..1..1..0....1..0..0....1..0..0
%K nonn
%O 1,2
%A _R. H. Hardin_ Sep 30 2010