%I #4 Dec 18 2015 18:18:11
%S 1,4,63,3861,912060,823931109,2827364948343,36639801307739070,
%T 1783839514317792934491
%N Number of n X n binary matrices with zero diagonal and directed 3loops in at most one direction (3loop: x(i,j)*x(j,k)*x(k,i)=1, and i,j,k all different)
%e Some solutions for n=4
%e ..0..0..1..1....0..0..0..1....0..1..0..1....0..1..1..1....0..0..1..0
%e ..1..0..1..0....1..0..0..0....1..0..1..1....1..0..0..1....0..0..0..0
%e ..0..1..0..0....0..1..0..0....1..0..0..1....1..1..0..0....0..1..0..1
%e ..1..0..0..0....1..1..1..0....0..1..0..0....1..0..1..0....0..1..0..0
%K nonn
%O 1,2
%A _R. H. Hardin_ Jun 14 2012
