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

1,1

Links

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

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

Example

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

Crossrefs

Column 3 of A295781.

Sequence in context: A032194 A024532 A036421 * A202658 A202118 A327821

Adjacent sequences: A295773 A295774 A295775 * A295777 A295778 A295779

Keyword

nonn

Author

R. H. Hardin, Nov 27 2017

Status

approved