A146131 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 3X2 zee 1,1 1,2 1,3 2,3 2,4 in any orientation.

1, 1, 1, 1, 1, 1, 5, 9, 21, 39, 159, 427, 2501, 9027, 58503, 271185, 2371669, 14600987, 167228191, 1344019107, 19775648697, 206847230557, 3987249030381, 54541478154327, 1370106516904685, 24431476697291095

Offset

1,7

Links

Table of n, a(n) for n=1..26.

Example

Maximal 8 X 8 example
.0.0.1.1.1.0.0.0
.0.0.0.0.1.1.0.0
.1.0.0.0.0.0.1.0
.1.0.0.0.0.0.1.1
.1.1.0.0.0.0.0.1
.0.1.0.0.0.0.0.1
.0.0.1.1.0.0.0.0
.0.0.0.1.1.1.0.0

Crossrefs

Sequence in context: A081883 A049744 A000323 * A083943 A097074 A050559

Adjacent sequences: A146128 A146129 A146130 * A146132 A146133 A146134

Keyword

nonn

Author

R. H. Hardin, Oct 27 2008

Status

approved