A147281 Number of n X n binary arrays symmetric under 90 degree rotation with all ones connected only in a 1000-1100-0111-0001 pattern in any orientation.

1, 1, 1, 1, 1, 1, 1, 1, 21, 49, 87, 289, 1009, 3425, 11605, 48481, 255569, 1441107, 8859577, 59249469, 422335799

Offset

1,9

Links

Table of n, a(n) for n=1..21.

Example

Maximal 9 X 9 example
.0.0.0.1.1.0.0.0.0
.0.0.0.0.1.1.0.0.0
.0.0.0.1.0.1.0.0.0
.0.1.1.1.0.1.1.0.1
.1.1.0.0.0.0.0.1.1
.1.0.1.1.0.1.1.1.0
.0.0.0.1.0.1.0.0.0
.0.0.0.1.1.0.0.0.0
.0.0.0.0.1.1.0.0.0

Crossrefs

Sequence in context: A020178 A347372 A141556 * A130062 A153441 A357679

Adjacent sequences: A147278 A147279 A147280 * A147282 A147283 A147284

Keyword

nonn

Author

R. H. Hardin, Nov 04 2008

Status

approved