login
A183323
Number of n X n binary arrays with each 1 adjacent to exactly two other 1s
0
1, 2, 6, 27, 289, 4740, 128371, 6115158, 505971397, 73890230419, 19136191954838, 8704355999401819, 6908686513461201175, 9552034660752931158279
OFFSET
1,2
COMMENTS
Diagonal of A183328
EXAMPLE
Some solutions for 6X6
..1..1..1..0..0..0....0..1..1..1..1..0....0..0..0..1..1..1....0..0..1..1..1..1
..1..0..1..0..1..1....0..1..0..0..1..1....0..0..1..1..0..1....0..0..1..0..0..1
..1..0..1..0..1..1....1..1..0..0..0..1....0..1..1..0..1..1....1..1..1..0..0..1
..1..1..1..0..0..0....1..0..0..0..1..1....0..1..0..1..1..0....1..0..0..0..0..1
..0..0..0..1..1..0....1..1..0..1..1..0....0..1..0..1..0..0....1..0..0..0..1..1
..0..0..0..1..1..0....0..1..1..1..0..0....0..1..1..1..0..0....1..1..1..1..1..0
CROSSREFS
Sequence in context: A003513 A113731 A113676 * A153253 A174880 A303394
KEYWORD
nonn
AUTHOR
R. H. Hardin Jan 03 2011
STATUS
approved