A213599 - OEIS

A213599

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)

1, 3, 25, 549, 30535, 4168935, 1362083785, 1042729407045

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

EXAMPLE

Some solutions for n=4

..0..0..0..0....0..0..0..0....0..1..1..0....0..0..1..0....0..1..0..1

..1..0..1..0....0..0..0..1....0..0..0..0....1..0..1..1....0..0..0..1

..1..0..0..0....0..0..0..1....0..1..0..0....0..0..0..0....1..0..0..0

..0..0..0..0....0..0..0..0....0..0..1..0....0..0..1..0....0..0..0..0

CROSSREFS

KEYWORD

nonn

AUTHOR

STATUS

approved