A299590 Number of n X 3 0..1 arrays with every element unequal to 0, 1 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

3, 3, 5, 11, 19, 35, 65, 120, 220, 404, 744, 1369, 2517, 4629, 8515, 15662, 28806, 52982, 97450, 179239, 329671, 606359, 1115269, 2051300, 3772928, 6939496, 12763724, 23476149, 43179369, 79419241, 146074759, 268673370, 494167370, 908915498

Offset: 1

Author

R. H. Hardin, Feb 13 2018

Keywords

• nonn

Comments

Column 3 of A299595.

Examples

			Some solutions for n=5:
..0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..1..0. .0..0..0. .0..0..0
..0..0..0. .1..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .1..0..0
..0..0..0. .0..0..1. .0..0..0. .1..0..0. .0..0..0. .0..0..1. .0..0..0
..0..0..0. .0..0..0. .1..0..0. .0..0..0. .0..0..1. .0..0..0. .0..0..0
..0..1..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0
		

Links

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

Crossrefs

Cf. A299595.

Formula

Empirical: a(n) = a(n-1) +2*a(n-3) +a(n-4) +a(n-5) for n>8.

Empirical g.f.: x*(3 + 2*x^2 - x^4 + x^7) / ((1 + x^2)*(1 - x - x^2 - x^3)). - Colin Barker, Feb 15 2018