A146130 Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 3X2 zee 1,1 1,2 1,3 2,3 2,4 in any orientation.

1, 1, 1, 1, 5, 17, 59, 325, 2193, 20593, 247017, 3816169, 76385445, 1998729963, 68606304143, 3070344768595, 178823377788539, 13583194771026533, 1345184891829774733

Offset

1,5

Links

Table of n, a(n) for n=1..19.

Example

Maximal 8 X 8 example
.0.0.0.0.1.1.1.0
.0.0.1.1.0.0.1.1
.0.1.0.1.1.1.0.0
.0.1.1.0.0.0.1.0
.1.0.1.0.0.0.1.0
.1.0.1.0.0.0.1.1
.1.1.0.1.1.1.0.1
.0.1.0.0.0.1.1.0

Crossrefs

Sequence in context: A149659 A149660 A149661 * A026619 A142956 A273422

Adjacent sequences: A146127 A146128 A146129 * A146131 A146132 A146133

Keyword

nonn

Author

R. H. Hardin, Oct 27 2008

Status

approved