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

Author

R. H. Hardin, Apr 16 2014

Keywords

• nonn

Examples

			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
		

Links

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

Crossrefs

Column 3 of A241108.

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