A211050 1/3 the number of n X n 0..2 symmetric matrices with every element equal to two or three horizontal and vertical neighbors

0, 1, 1, 11, 69, 1059, 21565, 767763, 42018069, 3765457981, 536609175439, 123351155903565, 45453341030199701, 26933811670713434089

Offset

1,4

Links

Table of n, a(n) for n=1..14.

Example

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

Crossrefs

Sequence in context: A182188 A099336 A236320 * A295074 A173200 A071746

Adjacent sequences: A211047 A211048 A211049 * A211051 A211052 A211053

Keyword

nonn

Author

R. H. Hardin Mar 30 2012

Status

approved