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%I #2 Mar 31 2012 12:35:49
%S 2,8,182,49772,113400002,4027811102702,1237505791330809002
%N Number of (2*n)Xn binary matrices with all row sums equal and all column sums equal
%C Column 2 of A181236
%e Some solutions for 6X3
%e ..1..0..0....0..1..1....1..0..0....1..1..0....0..1..0....1..0..0....0..0..1
%e ..0..1..0....1..0..1....0..1..0....1..1..0....1..0..0....0..0..1....1..0..0
%e ..1..0..0....1..1..0....0..0..1....0..1..1....0..0..1....0..1..0....0..1..0
%e ..0..0..1....1..1..0....0..0..1....0..1..1....0..1..0....0..1..0....1..0..0
%e ..0..0..1....0..1..1....1..0..0....1..0..1....0..0..1....0..0..1....0..1..0
%e ..0..1..0....1..0..1....0..1..0....1..0..1....1..0..0....1..0..0....0..0..1
%K nonn
%O 1,1
%A _R. H. Hardin_ Oct 10 2010