A296946 Number of n X 2 0..1 arrays with each 1 adjacent to 1, 3 or 5 king-move neighboring 1s.

2, 8, 16, 36, 112, 256, 608, 1680, 4064, 9920, 25984, 64320, 159232, 407296, 1017344, 2536704, 6420992, 16093184, 40271872, 101471232, 254636032, 638328832, 1605165056, 4029763584, 10110525440, 25402425344, 63780978688, 160088997888

Offset: 1

Author

R. H. Hardin, Dec 22 2017

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 2 of A296952.

Formula

Empirical: a(n) = 2*a(n-1) + 8*a(n-3) - 12*a(n-4).

Empirical g.f.: 2*x*(1 + 2*x - 6*x^3) / (1 - 2*x - 8*x^3 + 12*x^4). - Colin Barker, Feb 25 2019