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%I #4 Dec 18 2015 18:18:11
%S 1,3,25,549,30535,4168935,1362083785,1042729407045
%N Number of n X n binary matrices with zero diagonal and no 2-loops or directed 3-loops (3-loop: 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..0..0....0..0..0..0....0..1..1..0....0..0..1..0....0..1..0..1
%e ..1..0..1..0....0..0..0..1....0..0..0..0....1..0..1..1....0..0..0..1
%e ..1..0..0..0....0..0..0..1....0..1..0..0....0..0..0..0....1..0..0..0
%e ..0..0..0..0....0..0..0..0....0..0..1..0....0..0..1..0....0..0..0..0
%K nonn
%O 1,2
%A _R. H. Hardin_ Jun 14 2012
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