A146640 Number of n X n binary arrays symmetric under 90 degree rotation with all ones connected only in a 1010-1111-0100 pattern in any orientation.

1, 1, 1, 1, 1, 1, 5, 17, 43, 75, 161, 539, 2129, 8565, 42667, 183445, 1039641, 5959305, 43560487, 311334093, 2752013037

Offset

1,7

Links

Table of n, a(n) for n=1..21.

Example

Maximal 8 X 8 example
.0.1.0.0.1.0.1.0
.1.1.0.0.1.1.1.1
.0.1.1.0.0.1.0.0
.1.1.0.0.0.0.0.0
.0.0.0.0.0.0.1.1
.0.0.1.0.0.1.1.0
.1.1.1.1.0.0.1.1
.0.1.0.1.0.0.1.0

Crossrefs

Sequence in context: A231703 A265193 A146720 * A100705 A100662 A168617

Adjacent sequences: A146637 A146638 A146639 * A146641 A146642 A146643

Keyword

nonn

Author

R. H. Hardin, Nov 04 2008

Status

approved