A146721 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 1100-1111-1000 pattern in any orientation.

1, 1, 1, 1, 5, 21, 49, 265, 1337, 7025, 55305, 543439, 6271235, 94294061, 1709408045, 38060613237

Offset

1,5

Links

Table of n, a(n) for n=1..16.

Example

Maximal 8 X 8 example
.0.1.1.1.0.1.1.1
.0.1.1.0.0.0.1.1
.0.0.1.0.0.0.1.0
.0.0.1.0.0.0.1.0
.0.1.0.0.0.1.0.0
.0.1.0.0.0.1.0.0
.1.1.0.0.0.1.1.0
.1.1.1.0.1.1.1.0

Crossrefs

Sequence in context: A041825 A022268 A201279 * A099979 A366723 A039659

Adjacent sequences: A146718 A146719 A146720 * A146722 A146723 A146724

Keyword

nonn

Author

R. H. Hardin, Nov 04 2008

Status

approved