A146057 Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 2X3 U in any orientation.

1, 1, 1, 1, 5, 13, 31, 133, 759, 5033, 38887, 382421, 4832387, 75700651, 1478349269, 35999240895, 1090549247319, 41238833131575, 1952862897511921, 115606424326327149, 8526463138185345657, 783968967361577289677

Offset

1,5

Links

Table of n, a(n) for n=1..22.

Example

Maximal 8 X 8 example
.0.0.0.1.1.0.0.0
.0.0.0.1.0.0.0.0
.0.0.0.1.1.0.0.0
.1.1.1.0.0.1.0.1
.1.0.1.0.0.1.1.1
.0.0.0.1.1.0.0.0
.0.0.0.0.1.0.0.0
.0.0.0.1.1.0.0.0

Crossrefs

Sequence in context: A146376 A146368 A147424 * A062403 A066688 A046789

Adjacent sequences: A146054 A146055 A146056 * A146058 A146059 A146060

Keyword

nonn

Author

R. H. Hardin, Oct 26 2008

Status

approved