A146678 Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 1100-0111-1100 pattern in any orientation.

1, 1, 1, 1, 1, 1, 1, 1, 4, 7, 14, 21, 42, 97, 337, 907, 3367, 9291, 36318, 129686, 674043, 2983615, 17944470, 88292506, 606666014, 3595901269, 30553144868, 219341547026

Offset

1,9

Links

Table of n, a(n) for n=1..28.

Example

Maximal 9 X 9 example
.0.0.0.0.1.1.0.0.0
.0.0.1.1.1.0.0.0.0
.0.1.0.0.1.1.0.0.0
.0.1.0.0.0.0.1.0.1
.1.1.1.0.0.0.1.1.1
.1.0.1.0.0.0.0.1.0
.0.0.0.1.1.0.0.1.0
.0.0.0.0.1.1.1.0.0
.0.0.0.1.1.0.0.0.0

Crossrefs

Sequence in context: A147372 A201272 A147440 * A146417 A008370 A291877

Adjacent sequences: A146675 A146676 A146677 * A146679 A146680 A146681

Keyword

nonn

Author

R. H. Hardin, Nov 04 2008

Status

approved