A303714 Number of n X 3 0..1 arrays with every element unequal to 0, 1 or 5 king-move adjacent elements, with upper left element zero.

3, 3, 5, 8, 14, 24, 40, 68, 116, 196, 332, 564, 956, 1620, 2748, 4660, 7900, 13396, 22716, 38516, 65308, 110740, 187772, 318388, 539868, 915412, 1552188, 2631924, 4462748, 7567124, 12830972, 21756468, 36890716, 62552660, 106065596, 179847028

Offset: 1

Author

R. H. Hardin, Apr 29 2018

Keywords

• nonn

Comments

Column 3 of A303719.

Examples

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

Links

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

Crossrefs

Cf. A303719.

Formula

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

Empirical g.f.: 3*x-x^2*(3+2*x+3*x^2)/(-1+x+2*x^3). - R. J. Mathar, Apr 30 2018