A147128 Number of n X n binary arrays symmetric about the diagonal and under 90 degree rotation with all ones connected only in a 1000-1000-1111-1000 pattern in any orientation.

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 9, 9, 23, 23, 55, 55, 223

Offset

1,13

Links

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

Crossrefs

Sequence in context: A232023 A146695 A146442 * A147214 A146820 A146663

Adjacent sequences: A147125 A147126 A147127 * A147129 A147130 A147131

Keyword

nonn

Author

R. H. Hardin, Nov 04 2008

Status

approved