A241103 Number of n X 3 0..2 arrays with no element equal to one or three horizontal or vertical neighbors, with new values 0..2 introduced in row major order.

2, 11, 58, 294, 1522, 7846, 40418, 208374, 1074002, 5535686, 28533058, 147068694, 758041522, 3907203046, 20139040418, 103803409974, 535037802002, 2757765332486, 14214452973058, 73266086411094, 377638128337522

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 8*a(n-2) + 16*a(n-3).

Empirical g.f.: x*(2 + 5*x + 9*x^2) / (1 - 3*x - 8*x^2 - 16*x^3). - Colin Barker, Oct 29 2018

Example

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

Crossrefs

Column 3 of A241108.

Sequence in context: A054130 A037738 A037633 * A162771 A020057 A363646

Adjacent sequences: A241100 A241101 A241102 * A241104 A241105 A241106

Keyword

nonn

Author

R. H. Hardin, Apr 16 2014

Status

approved