A146664 Number of n X n binary arrays symmetric under 90 degree rotation with all ones connected only in a 1100-0111-0001 pattern in any orientation.

1, 1, 1, 1, 1, 1, 3, 19, 43, 87, 303, 1077, 3757, 15681, 80673, 475263, 2975253, 20229343, 160250909, 1366441107, 13345035623

Offset

1,7

Links

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

Example

Maximal 8 X 8 example
.0.0.0.0.0.1.1.0
.1.0.0.1.1.1.0.0
.1.1.0.1.0.0.0.0
.0.1.0.0.0.1.1.0
.0.1.1.0.0.0.1.0
.0.0.0.0.1.0.1.1
.0.0.1.1.1.0.0.1
.0.1.1.0.0.0.0.0

Crossrefs

Sequence in context: A146704 A103145 A100694 * A028880 A162905 A201875

Adjacent sequences: A146661 A146662 A146663 * A146665 A146666 A146667

Keyword

nonn

Author

R. H. Hardin, Nov 04 2008

Status

approved