A146022 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 2X4 el 1,1 1,2 1,3 1,4 2,4 with any orientation.

1, 1, 1, 5, 21, 39, 231, 1367, 12771, 121235, 1706171, 26315137, 652740079, 17081149001

Offset

1,4

Links

Table of n, a(n) for n=1..14.

Example

Maximal 8 X 8 example
.0.0.0.1.1.1.1.0
.1.0.0.0.0.0.1.0
.1.1.1.1.0.0.0.1
.0.0.0.0.1.1.1.1
.1.1.1.1.0.0.0.0
.1.0.0.0.1.1.1.1
.0.1.0.0.0.0.0.1
.0.1.1.1.1.0.0.0

Crossrefs

Sequence in context: A365767 A372518 A147345 * A054286 A366346 A031292

Adjacent sequences: A146019 A146020 A146021 * A146023 A146024 A146025

Keyword

nonn

Author

R. H. Hardin, Oct 26 2008

Status

approved