A191691 Number of n X n symmetric binary matrices with each 1 adjacent to no more than 1 E, SE or S neighboring 1

2, 6, 32, 294, 4640, 125338, 5802288, 459958324, 62453890000, 14523496866976, 5784570667981520, 3945961499388113436, 4610186764537663968556, 9225021921428355206788506, 31615478219055162849230486428

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..24

Example

Some solutions for n=5
..0..1..0..0..1....0..0..0..1..0....1..0..1..0..0....1..0..1..0..1
..1..1..0..0..1....0..1..0..0..1....0..0..0..1..0....0..0..1..0..1
..0..0..0..0..1....0..0..1..0..0....1..0..0..0..0....1..1..0..0..0
..0..0..0..0..0....1..0..0..0..0....0..1..0..0..1....0..0..0..1..0
..1..1..1..0..0....0..1..0..0..1....0..0..0..1..0....1..1..0..0..0

Crossrefs

Sequence in context: A346270 A133596 A088437 * A191712 A277475 A277484

Adjacent sequences: A191688 A191689 A191690 * A191692 A191693 A191694

Keyword

nonn

Author

R. H. Hardin Jun 11 2011

Status

approved