A146055 Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 2X3 U in any orientation.

1, 1, 5, 1, 19, 9, 285, 231, 16083, 5087, 1835713, 304405, 353122721, 80250539, 202921921043, 41930288075, 327077447429739, 40565746729487, 1135093267840644915, 110051860951495273, 8965200194852051792065

Offset

1,3

Links

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

Example

Maximal 8 X 8 example
.1.1.1.0.0.1.1.1
.1.0.1.0.0.1.0.1
.0.0.0.0.0.0.0.0
.1.0.1.0.0.1.0.1
.1.1.1.0.0.1.1.1
.0.0.0.0.0.0.0.0
.1.1.1.0.0.1.1.1
.1.0.1.0.0.1.0.1

Crossrefs

Sequence in context: A193861 A349544 A193857 * A286232 A147437 A147369

Adjacent sequences: A146052 A146053 A146054 * A146056 A146057 A146058

Keyword

nonn

Author

R. H. Hardin, Oct 26 2008

Status

approved