A140421 Number of n X n symmetric binary matrices with every element adjacent to some zero horizontally or vertically.

3, 13, 160, 2817, 119145, 8890880, 1270451663, 347961207321, 183722336587008, 185316870246113925, 357804006282379850529, 1323503980097432239521792, 9379216327375443934023725295, 127291943357342220975708211213101

Offset

2,1

Links

Table of n, a(n) for n=2..15.

Crossrefs

Sequence in context: A224990 A065622 A246418 * A176315 A290758 A290769

Adjacent sequences: A140418 A140419 A140420 * A140422 A140423 A140424

Keyword

nonn

Author

R. H. Hardin, Jun 18 2008

Status

approved