A147126 Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 1000-1000-1111-1000 pattern in any orientation.

1, 1, 1, 1, 1, 3, 9, 23, 55, 223, 1115, 7199, 49215, 368043, 3428835, 40706551, 594200493, 10158791409, 204811760131, 4951116757551, 144268283766901

Offset

1,6

Links

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

Example

Maximal 8 X 8 example
.0.0.0.0.0.0.0.0
.0.0.0.0.0.0.0.0
.0.0.0.0.0.0.0.1
.0.0.0.0.1.1.1.1
.0.0.0.1.0.0.0.1
.0.0.0.1.0.0.0.1
.0.0.0.1.0.0.0.0
.0.0.1.1.1.1.0.0

Crossrefs

Sequence in context: A183155 A305168 A274099 * A147212 A341029 A045883

Adjacent sequences: A147123 A147124 A147125 * A147127 A147128 A147129

Keyword

nonn

Author

R. H. Hardin, Nov 04 2008

Status

approved