A211092 1/4 the number of n X n 0..3 symmetric matrices with every element equal to two or three horizontal and vertical neighbors

0, 1, 1, 19, 136, 3496, 100204, 6012109, 537556135, 86449986124, 22576823498161, 10130717811503530, 7577956550025798379

Offset

1,4

Links

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

Example

Some solutions for n=4
..3..3..2..2....0..0..2..2....3..3..0..0....2..2..2..2....3..3..1..1
..3..3..2..2....0..0..2..2....3..3..0..0....2..2..2..2....3..3..1..1
..2..2..2..2....2..2..3..3....0..0..0..0....2..2..3..3....1..1..1..1
..2..2..2..2....2..2..3..3....0..0..0..0....2..2..3..3....1..1..1..1

Crossrefs

Sequence in context: A215863 A101090 A213122 * A142746 A221226 A139902

Adjacent sequences: A211089 A211090 A211091 * A211093 A211094 A211095

Keyword

nonn

Author

R. H. Hardin Mar 31 2012

Status

approved