A146157 Number of n X n binary arrays symmetric about the diagonal and under 90 degree rotation with all ones connected only either as two by three or three by two blocks.

1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 6, 7, 16, 23, 50, 65, 176, 221, 727, 1056, 3742, 5997, 23258, 37914, 168488, 284282, 1460179, 2612520, 15176540, 28767703

Offset

1,7

Links

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

Example

Maximal 8 X 8 example
.0.0.0.1.1.0.0.0
.0.0.0.1.1.0.0.0
.0.0.0.1.1.0.0.0
.1.1.1.0.0.1.1.1
.1.1.1.0.0.1.1.1
.0.0.0.1.1.0.0.0
.0.0.0.1.1.0.0.0
.0.0.0.1.1.0.0.0

Crossrefs

Sequence in context: A121211 A316585 A369765 * A238363 A255254 A048848

Adjacent sequences: A146154 A146155 A146156 * A146158 A146159 A146160

Keyword

nonn

Author

R. H. Hardin, Oct 27 2008

Status

approved