A145959 Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a zee 1,1 1,2 2,2 2,3 in any orientation.

1, 1, 1, 5, 17, 75, 405, 2821, 26895, 365651, 6440881, 149278281, 4554728635, 183204987539, 9796495036771, 702723336742467

Offset

1,4

Links

Table of n, a(n) for n=1..16.

Example

Maximal 8 X 8 example
.0.1.1.0.0.0.1.0
.1.1.0.0.1.0.1.1
.0.0.0.1.1.0.0.1
.1.1.0.1.0.1.1.0
.0.1.1.0.1.0.1.1
.1.0.0.1.1.0.0.0
.1.1.0.1.0.0.1.1
.0.1.0.0.0.1.1.0

Crossrefs

Sequence in context: A149734 A149735 A149736 * A126956 A149737 A149738

Adjacent sequences: A145956 A145957 A145958 * A145960 A145961 A145962

Keyword

nonn

Author

R. H. Hardin, Oct 25 2008

Status

approved