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A181235 Number of (3*n)Xn binary matrices with all row sums equal and all column sums equal.

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%I A181235 #4 Jul 22 2025 08:38:01
%S A181235 2,22,3362,33235358,5210265060002,90698868503010138802
%N A181235 Number of (3*n)Xn binary matrices with all row sums equal and all column sums equal.
%C A181235 Column 3 of A181236
%e A181235 Some solutions for 9X3
%e A181235 ..0..1..1....0..1..1....1..1..0....0..0..1....1..0..0....1..0..1....0..1..0
%e A181235 ..0..1..1....1..0..1....1..0..1....0..1..0....0..1..0....1..0..1....1..0..0
%e A181235 ..1..1..0....1..0..1....0..1..1....1..0..0....0..0..1....1..1..0....0..1..0
%e A181235 ..1..1..0....1..1..0....0..1..1....1..0..0....1..0..0....1..0..1....0..1..0
%e A181235 ..0..1..1....0..1..1....1..1..0....0..1..0....1..0..0....0..1..1....0..0..1
%e A181235 ..1..0..1....0..1..1....1..0..1....1..0..0....0..0..1....0..1..1....1..0..0
%e A181235 ..1..0..1....1..1..0....1..0..1....0..0..1....0..0..1....0..1..1....0..0..1
%e A181235 ..1..1..0....1..1..0....0..1..1....0..0..1....0..1..0....1..1..0....0..0..1
%e A181235 ..1..0..1....1..0..1....1..1..0....0..1..0....0..1..0....1..1..0....1..0..0
%K A181235 nonn
%O A181235 1,1
%A A181235 _R. H. Hardin_ Oct 10 2010

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