A213545 - OEIS

A213545

Number of n X n binary matrices with zero diagonal and directed 3-loops in at most one direction (3-loop: x(i,j)*x(j,k)*x(k,i)=1, and i,j,k all different)

%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 3-loops in at most one direction (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..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