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A181234 Number of (2*n)Xn binary matrices with all row sums equal and all column sums equal.

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%I A181234 #4 Jul 22 2025 08:37:54
%S A181234 2,8,182,49772,113400002,4027811102702,1237505791330809002
%N A181234 Number of (2*n)Xn binary matrices with all row sums equal and all column sums equal.
%C A181234 Column 2 of A181236
%e A181234 Some solutions for 6X3
%e A181234 ..1..0..0....0..1..1....1..0..0....1..1..0....0..1..0....1..0..0....0..0..1
%e A181234 ..0..1..0....1..0..1....0..1..0....1..1..0....1..0..0....0..0..1....1..0..0
%e A181234 ..1..0..0....1..1..0....0..0..1....0..1..1....0..0..1....0..1..0....0..1..0
%e A181234 ..0..0..1....1..1..0....0..0..1....0..1..1....0..1..0....0..1..0....1..0..0
%e A181234 ..0..0..1....0..1..1....1..0..0....1..0..1....0..0..1....0..0..1....0..1..0
%e A181234 ..0..1..0....1..0..1....0..1..0....1..0..1....1..0..0....1..0..0....0..0..1
%K A181234 nonn
%O A181234 1,1
%A A181234 _R. H. Hardin_ Oct 10 2010

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