A192641 Number of n X n symmetric 0..4 arrays with each element equal to at least one horizontal or vertical neighbor and any new values 0..4 introduced in lower triangular row major order

0, 1, 5, 137, 17487, 11679460, 29893061411, 272547393058796, 8435849125548477470, 886985453412974633027297

Offset

1,3

Links

Table of n, a(n) for n=1..10.

Example

Some solutions for 6X6 containing a 4
..0..0..0..0..0..1....0..0..0..1..2..2....0..0..0..1..1..3....0..0..0..0..2..2
..0..0..0..2..2..1....0..0..0..1..3..3....0..0..0..2..3..3....0..0..0..1..1..1
..0..0..1..1..4..4....0..0..0..1..2..1....0..0..0..2..1..2....0..0..0..2..2..3
..0..2..1..3..3..4....1..1..1..1..2..1....1..2..2..1..1..2....0..1..2..1..1..3
..0..2..4..3..3..4....2..3..2..2..2..4....1..3..1..1..4..4....2..1..2..1..1..4
..1..1..4..4..4..4....2..3..1..1..4..4....3..3..2..2..4..4....2..1..3..3..4..4

Crossrefs

Sequence in context: A012142 A012207 A192640 * A192642 A192643 A192644

Adjacent sequences: A192638 A192639 A192640 * A192642 A192643 A192644

Keyword

nonn

Author

R. H. Hardin Jul 06 2011

Status

approved