A146013 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 3X3 tee 1,1 1,2 1,3 2,2 3,2 in any orientation.

1, 1, 1, 1, 5, 23, 94, 401, 1988, 14721, 122901, 1562739, 20966035, 411218439, 8595065749, 245851647552, 7857204479253, 356188989672617

Offset

1,5

Links

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

Example

Maximal 8 X 8 example
.1.1.1.0.1.0.0.0
.0.1.0.0.1.1.1.0
.0.1.0.0.1.0.0.1
.1.0.0.0.0.1.1.1
.1.1.1.0.0.0.0.1
.1.0.0.1.0.0.1.0
.0.1.1.1.0.0.1.0
.0.0.0.1.0.1.1.1

Crossrefs

Sequence in context: A331720 A327973 A255457 * A028894 A254824 A140529

Adjacent sequences: A146010 A146011 A146012 * A146014 A146015 A146016

Keyword

nonn

Author

R. H. Hardin, Oct 26 2008

Status

approved