A232290 Number of n X 3 0..2 arrays with every 0 next to a 1 and every 1 next to a 2 horizontally or antidiagonally.

7, 97, 1313, 17759, 240241, 3249889, 43963319, 594719777, 8045152705, 108831897871, 1472238306545, 19915904010305, 269415101335399, 3644549440989793, 49302138454678241, 666941386187953343

Offset: 1

Author

R. H. Hardin, Nov 22 2013

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 3 of A232295.

Formula

Empirical: a(n) = 12*a(n-1) + 20*a(n-2) + 9*a(n-3).

Empirical g.f.: x*(7 + 13*x + 9*x^2) / (1 - 12*x - 20*x^2 - 9*x^3). - Colin Barker, Oct 04 2018