A297391 Number of n X 4 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 1 neighboring 1.

4, 13, 37, 126, 385, 1243, 3924, 12477, 39625, 125780, 399527, 1268481, 4028320, 12791471, 40619227, 128985178, 409588149, 1300636903, 4130132236, 13115120227, 41646681705, 132247843570, 419949219621, 1333536652989, 4234607278278

Offset: 1

Author

R. H. Hardin, Dec 29 2017

Keywords

• nonn

Examples

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

Column 4 of A297395.

Formula

Empirical: a(n) = a(n-1) + 6*a(n-2) + 4*a(n-3) - 3*a(n-4) - a(n-5) - 2*a(n-6) - a(n-7).

Empirical g.f.: x*(4 + 9*x - 5*x^3 - 3*x^4 - 3*x^5 - x^6) / (1 - x - 6*x^2 - 4*x^3 + 3*x^4 + x^5 + 2*x^6 + x^7). - Colin Barker, Feb 28 2019