A229689 Number of defective 3-colorings of an n X 3 0..2 array connected horizontally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..2 order.

1, 43, 626, 6732, 62856, 539568, 4377888, 34105536, 257634432, 1899645696, 13735899648, 97733495808, 686049232896, 4760622968832, 32708331380736, 222789318524928, 1506002505596928, 10111798278291456, 67486591206162432

Offset: 1

Author

R. H. Hardin, Sep 27 2013

Keywords

• nonn

Comments

Column 3 of A229694.

Examples

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

Links

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

Crossrefs

Cf. A229694.

Formula

Empirical: a(n) = 18*a(n-1) -108*a(n-2) +216*a(n-3) for n > 4.

Empirical: g.f. x -x^2*(43-148*x+108*x^2) / (6*x-1)^3. - R. J. Mathar, Sep 29 2013