A147480 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 1100-1111-1100 pattern in any orientation.

1, 1, 1, 1, 1, 9, 21, 73, 310, 1107, 5232, 33319, 240772, 2106289, 21011261, 262231181, 3633528079, 62517538899

Offset

1,6

Links

Table of n, a(n) for n=1..18.

Example

Maximal 8 X 8 example
.0.0.1.1.0.0.0.0
.1.1.1.1.0.0.0.0
.0.0.1.1.0.0.1.1
.1.1.0.0.1.1.1.1
.1.1.1.1.0.0.1.1
.1.1.0.0.1.1.0.0
.0.0.0.0.1.1.1.1
.0.0.0.0.1.1.0.0

Crossrefs

Sequence in context: A173084 A137340 A075640 * A146396 A146681 A269633

Adjacent sequences: A147477 A147478 A147479 * A147481 A147482 A147483

Keyword

nonn

Author

R. H. Hardin

Status

approved