A146048 Number of n X n binary arrays symmetric under horizontal and vertical reflection with all ones connected only in a 2X2 block with tail 1,1 1,2 1,3 2,2 2,3 in any orientation.

1, 1, 1, 1, 1, 1, 17, 17, 57, 57, 781, 781, 24351, 24351, 931801, 931801, 62200649, 62200649, 8963823755, 8963823755, 2146203654665, 2146203654665, 870522837091137, 870522837091137, 672438522925983773

Offset

1,7

Links

Table of n, a(n) for n=1..25.

Example

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

Crossrefs

Sequence in context: A147241 A146580 A146455 * A146809 A147233 A146817

Adjacent sequences: A146045 A146046 A146047 * A146049 A146050 A146051

Keyword

nonn

Author

R. H. Hardin, Oct 26 2008

Status

approved