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%I #3 Dec 18 2015 18:17:26
%S 1,2,6,71,2403,238535,73506103,64732546521,189964969385932,
%T 1647943050926969975
%N Number of n X n binary matrices with floor(n^2/2) 1's and rows in lexicographically nondecreasing order and columns in strictly increasing order
%C Diagonal of A180983
%e All solutions for 3X3
%e ..0..0..0....0..0..1....0..0..1....0..0..1....0..0..1....0..0..1
%e ..0..1..1....0..1..0....0..0..1....0..1..0....0..1..0....0..1..1
%e ..1..0..1....0..1..1....0..1..1....1..1..0....1..0..1....1..0..0
%K nonn
%O 1,2
%A _R. H. Hardin_ Sep 30 2010
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