A295776 Number of n X 3 0..1 arrays with each 1 adjacent to 0 or 2 king-move neighboring 1s.

5, 19, 56, 198, 665, 2213, 7479, 25105, 84326, 283532, 952661, 3201517, 10759441, 36157455, 121511416, 408352614, 1372308917, 4611790689, 15498404475, 52083999509, 175033735054, 588219141252, 1976771852673, 6643148349849

Offset: 1

Author

R. H. Hardin, Nov 27 2017

Keywords

• nonn

Examples

			Some solutions for n=7:
..1..1..0. .0..0..0. .1..0..0. .0..0..0. .0..0..1. .1..0..0. .0..0..0
..0..1..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..1. .0..1..0. .0..1..1. .0..0..0. .0..0..0
..0..1..1. .0..1..1. .1..0..0. .0..0..0. .0..0..1. .0..1..0. .1..0..0
..0..1..0. .0..1..0. .0..0..1. .1..0..1. .1..0..0. .1..0..1. .0..0..0
..0..0..0. .0..0..0. .1..0..0. .0..0..0. .1..1..0. .1..0..1. .0..1..0
..1..0..1. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..1..0. .0..1..1
		

Links

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

Crossrefs

Column 3 of A295781.

Formula

Empirical: a(n) = 2*a(n-1) + 3*a(n-2) + 6*a(n-3) - 3*a(n-4) + 2*a(n-5).

Empirical g.f.: x*(5 + 9*x + 3*x^2 - x^3 + 2*x^4) / (1 - 2*x - 3*x^2 - 6*x^3 + 3*x^4 - 2*x^5). - Colin Barker, Feb 22 2019