A229581 Number of defective 3-colorings of an n X 3 0..2 array connected horizontally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..2 order.

2, 28, 264, 2160, 16416, 119232, 839808, 5785344, 39191040, 262020096, 1733363712, 11367641088, 74010599424, 478892113920, 3082323787776, 19747769352192, 126009575866368, 801195213717504, 5077997833420800, 32092946307219456

Offset: 1

Author

R. H. Hardin, Sep 26 2013

Keywords

• nonn

Examples

			Some solutions for n=3:
..0..1..1....0..1..2....0..0..1....0..1..2....0..1..2....0..1..2....0..1..0
..0..2..1....0..1..2....1..0..2....2..1..0....2..0..1....0..1..0....2..1..0
..0..2..1....0..2..0....2..1..0....2..2..0....2..2..1....0..1..1....2..2..0
		

Links

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

Crossrefs

Column 3 of A229586.

Formula

Empirical: a(n) = 12*a(n-1) - 36*a(n-2).

Conjectures from Colin Barker, Sep 19 2018: (Start)

G.f.: 2*(1 + 2*x) / (1 - 6*x)^2.

a(n) = 2^(n + 1) * 3^(n - 1) * (4*n + 3).

(End)