A146277 Number of n X n binary arrays symmetric about the diagonal and under 90 degree rotation with all ones connected only in a 110-111-111 pattern in any orientation.

1, 1, 1, 1, 1, 1, 3, 3, 5, 5, 9, 9, 21, 21, 93, 93, 381, 381, 1551, 1551, 7459, 7459, 56347, 56347, 473995, 473995, 4321181

Offset

1,7

Links

Table of n, a(n) for n=1..27.

Example

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

Crossrefs

Sequence in context: A146914 A146253 A147040 * A050822 A187494 A283843

Adjacent sequences: A146274 A146275 A146276 * A146278 A146279 A146280

Keyword

nonn

Author

R. H. Hardin

Status

approved