A147040 Number of n X n binary arrays symmetric about the diagonal and under 90 degree rotation with all ones connected only in a 0100-0100-1111-0100 pattern in any orientation.

1, 1, 1, 1, 1, 1, 1, 1, 3, 3, 5, 5, 9, 9, 21, 21, 69, 69, 305, 305, 1333, 1333, 6087, 6087, 37147, 37147, 280959, 280959

Offset

1,9

Links

Table of n, a(n) for n=1..28.

Example

Maximal 9 X 9 example
.0.0.1.0.0.0.1.0.0
.0.0.1.0.0.0.1.0.0
.1.1.1.1.0.1.1.1.1
.0.0.1.0.0.0.1.0.0
.0.0.0.0.0.0.0.0.0
.0.0.1.0.0.0.1.0.0
.1.1.1.1.0.1.1.1.1
.0.0.1.0.0.0.1.0.0
.0.0.1.0.0.0.1.0.0

Crossrefs

Sequence in context: A147472 A146914 A146253 * A146277 A050822 A187494

Adjacent sequences: A147037 A147038 A147039 * A147041 A147042 A147043

Keyword

nonn

Author

R. H. Hardin, Nov 04 2008

Status

approved