A229695 Number of defective 3-colorings of a 2Xn 0..2 array connected horizontally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..2 order.

0, 3, 43, 245, 1171, 5077, 20691, 80757, 305235, 1125333, 4067091, 14461173, 50723091, 175867605, 603736659, 2054728053, 6940088019, 23284024533, 77651501715, 257577229557, 850273182099, 2794463987157, 9147385165779

Offset: 1

Author

R. H. Hardin, Sep 27 2013

Keywords

• nonn

Comments

Row 2 of A229694

Examples

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

Links

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

Formula

Empirical: a(n) = 9*a(n-1) -27*a(n-2) +27*a(n-3) for n>6.

Empirical: G.f. 3*x^2+43*x^3 -x^4*(245-1034*x+1153*x^2) / (3*x-1)^3. - R. J. Mathar, Sep 29 2013