A146149 Number of n X n binary arrays symmetric about the diagonal and under 90 degree rotation with all ones connected only in an em 1,1 1,2 2,2 2,3 3,3 in any orientation.

1, 1, 1, 1, 1, 1, 3, 3, 7, 7, 17, 17, 57, 57, 295, 295, 1823, 1823, 12191, 12191, 109351, 109351, 1406131, 1406131, 21111023, 21111023, 390067193, 390067193, 9744306045, 9744306045

Offset

1,7

Links

Table of n, a(n) for n=1..30.

Example

Maximal 8 X 8 example
.0.0.1.0.0.1.0.0
.0.1.1.0.0.1.1.0
.1.1.0.0.0.0.1.1
.0.0.0.0.0.0.0.0
.0.0.0.0.0.0.0.0
.1.1.0.0.0.0.1.1
.0.1.1.0.0.1.1.0
.0.0.1.0.0.1.0.0

Crossrefs

Sequence in context: A226781 A147144 A152113 * A263795 A070925 A146687

Adjacent sequences: A146146 A146147 A146148 * A146150 A146151 A146152

Keyword

nonn

Author

R. H. Hardin, Oct 27 2008

Status

approved