A232453 Number of n X 2 0..2 arrays with every 0 next to a 1 and every 1 next to a 2 horizontally, vertically, diagonally or antidiagonally.

3, 51, 381, 3015, 24651, 198945, 1607067, 12991131, 104990445, 848511855, 6857610579, 55422433089, 447917887827, 3620023336611, 29256629564061, 236448855048951, 1910953595190267, 15444116384727393, 124817646797556651

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 6*a(n-1) + 12*a(n-2) + 39*a(n-3).

Empirical g.f.: 3*x*(1 + 11*x + 13*x^2) / (1 - 6*x - 12*x^2 - 39*x^3). - Colin Barker, Oct 05 2018

Example

Some solutions for n=6:
..1..0....1..1....0..2....0..2....1..1....0..1....1..0....0..1....0..2....1..1
..2..1....2..2....1..2....2..1....2..0....1..2....2..1....2..2....1..0....0..2
..1..0....1..2....1..2....1..0....2..2....1..0....2..2....2..2....0..0....0..2
..0..0....1..2....0..1....1..1....2..2....2..2....2..2....1..0....0..1....1..1
..0..1....2..1....1..2....2..0....1..2....0..2....1..2....0..2....1..2....2..1
..2..2....0..1....0..0....1..0....0..1....2..1....1..1....0..1....2..1....1..2

Crossrefs

Column 2 of A232459.

Sequence in context: A116630 A317455 A045489 * A248341 A145242 A182512

Adjacent sequences: A232450 A232451 A232452 * A232454 A232455 A232456

Keyword

nonn

Author

R. H. Hardin, Nov 24 2013

Status

approved