A146638 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 1010-1111-0100 pattern in any orientation.

1, 1, 1, 1, 1, 1, 1, 3, 9, 19, 33, 57, 181, 727, 3143, 12709, 46177, 203713, 1168453, 7869343, 57494841, 429662591, 3357500475

Offset

1,8

Links

Table of n, a(n) for n=1..23.

Example

Maximal 8 X 8 example
.0.0.0.1.0.1.0.0
.0.0.1.1.1.1.0.0
.0.1.0.0.1.0.1.1
.1.1.0.0.0.1.1.0
.0.1.1.0.0.0.1.1
.1.1.0.1.0.0.1.0
.0.0.1.1.1.1.0.0
.0.0.1.0.1.0.0.0

Crossrefs

Sequence in context: A328950 A049749 A147055 * A147135 A146843 A146630

Adjacent sequences: A146635 A146636 A146637 * A146639 A146640 A146641

Keyword

nonn

Author

R. H. Hardin, Nov 04 2008

Status

approved