A146253 Number of n X n binary arrays symmetric about the diagonal and under 90 degree rotation with all ones connected only in a 110-111-011 pattern in any orientation.

1, 1, 1, 1, 1, 1, 3, 3, 5, 5, 9, 9, 19, 19, 71, 71, 265, 265, 1031, 1031, 4533, 4533, 26975, 26975, 188011, 188011, 1487007, 1487007, 13567107, 13567107

Offset

1,7

Links

Table of n, a(n) for n=1..30.

Example

Maximal 8 X 8 example
.1.1.0.0.0.0.1.1
.1.1.1.0.0.1.1.1
.0.1.1.0.0.1.1.0
.0.0.0.0.0.0.0.0
.0.0.0.0.0.0.0.0
.0.1.1.0.0.1.1.0
.1.1.1.0.0.1.1.1
.1.1.0.0.0.0.1.1

Crossrefs

Sequence in context: A049644 A147472 A146914 * A147040 A146277 A050822

Adjacent sequences: A146250 A146251 A146252 * A146254 A146255 A146256

Keyword

nonn

Author

R. H. Hardin

Status

approved