A183329 Number of n X n binary arrays with each 1 adjacent to exactly two 0's.

1, 7, 26, 247, 4643, 135578, 7279940, 684911503, 111613234643, 31882671447699, 15903381470791210, 13849831552030467450, 21073883712902398984415

Offset

1,2

Comments

Diagonal of A183335.

Links

Table of n, a(n) for n=1..13.

Example

Some solutions for 6 X 6
..1..0..1..0..0..0....0..0..0..0..1..0....0..1..0..0..0..0....1..0..0..1..0..1
..0..0..1..1..1..0....1..1..1..0..1..1....1..1..0..0..0..0....0..0..1..1..0..0
..1..1..0..0..1..1....0..0..1..0..0..0....0..0..1..1..0..0....0..0..1..0..0..0
..0..1..0..0..0..0....0..1..1..0..1..1....0..0..1..1..0..0....0..1..1..0..0..0
..1..1..0..1..1..1....0..1..0..1..1..0....0..0..0..0..0..0....0..1..0..0..1..1
..0..0..0..1..0..0....0..1..0..1..0..1....1..0..1..1..0..0....0..1..0..0..1..0

Crossrefs

Sequence in context: A197053 A009375 A009380 * A342930 A166406 A243006

Adjacent sequences: A183326 A183327 A183328 * A183330 A183331 A183332

Keyword

nonn

Author

R. H. Hardin Jan 03 2011

Status

approved