A139012 Number of n X n symmetric binary matrices containing no more than three 1s in any 3 X 3 sub-block.

1, 2, 7, 20, 146, 1660, 24266, 619885, 24951532, 1491389352, 141842503743, 21156539568960, 4861988525864115, 1744688422871068399, 977626718408600885914, 851525107752786868842753

Offset

0,2

Links

Table of n, a(n) for n=0..15.

Crossrefs

Sequence in context: A189771 A260504 A009697 * A132605 A088157 A352017

Adjacent sequences: A139009 A139010 A139011 * A139013 A139014 A139015

Keyword

nonn

Author

R. H. Hardin, May 31 2008

Status

approved