A192640 Number of n X n symmetric 0..3 arrays with each element equal to at least one horizontal or vertical neighbor and any new values 0..3 introduced in lower triangular row major order.

0, 1, 5, 137, 15055, 5986313, 7174532375, 25969938730579, 281423389721323932, 9146849687492666154781, 891167854920321677292610251

Offset

1,3

Links

Table of n, a(n) for n=1..11.

Example

Some solutions for 6X6 containing a 3
..0..0..0..0..3..3....0..0..0..0..3..3....0..0..0..0..1..1....0..0..0..0..1..1
..0..0..0..2..2..2....0..0..0..1..1..0....0..0..0..0..0..0....0..0..0..2..2..1
..0..0..1..1..3..3....0..0..1..1..1..0....0..0..0..1..1..0....0..0..1..1..3..3
..0..2..1..0..0..0....0..1..1..2..2..0....0..0..1..1..2..2....0..2..1..2..2..3
..3..2..3..0..0..3....3..1..1..2..2..0....1..0..1..2..2..3....1..2..3..2..2..1
..3..2..3..0..3..3....3..0..0..0..0..0....1..0..0..2..3..3....1..1..3..3..1..1

Crossrefs

Sequence in context: A012215 A012142 A012207 * A192641 A192642 A192643

Adjacent sequences: A192637 A192638 A192639 * A192641 A192642 A192643

Keyword

nonn

Author

R. H. Hardin, Jul 06 2011

Status

approved