A188986 Number of n X 3 binary arrays without the pattern 0 0 1 antidiagonally or horizontally.

7, 49, 295, 1793, 10871, 65937, 399911, 2425505, 14710935, 89223345, 541148807, 3282123457, 19906418039, 120734483153, 732267120743, 4441275782369, 26936796718423, 163374456576241, 990882967287879, 6009807624994561

Offset: 1

Author

R. H. Hardin, Apr 15 2011

Keywords

• nonn

Comments

Column 3 of A188992.

Examples

			Some solutions for 4 X 3:
..1..0..0....0..1..0....0..0..0....1..1..0....0..0..0....1..0..0....1..0..0
..1..1..1....0..1..0....0..1..0....1..0..0....0..1..1....1..0..1....1..0..0
..0..0..0....1..1..0....1..1..1....0..1..1....1..0..0....0..1..1....0..0..0
..0..1..1....1..1..0....0..0..0....0..1..1....1..0..0....1..0..0....0..1..1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A188992.

Formula

Empirical: a(n) = 6*a(n-1) +a(n-2) -4*a(n-3) +2*a(n-4).

Empirical g.f.: x*(7 + 7*x - 6*x^2 + 2*x^3) / ((1 + x)*(1 - 7*x + 6*x^2 - 2*x^3)). - Colin Barker, May 01 2018