A301836 Number of n X 3 0..1 arrays with every element equal to 0, 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero.

4, 25, 139, 773, 4299, 23909, 132971, 739525, 4112907, 22874149, 127215787, 707517317, 3934894923, 21884125925, 121709722091, 676895047237, 3764587553931, 20936952499621, 116441967065899, 647598149464325

Offset: 1

Author

R. H. Hardin, Mar 27 2018

Keywords

• nonn

Comments

Column 3 of A301841.

Examples

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

Links

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

Crossrefs

Cf. A301841.

Formula

Empirical: a(n) = 7*a(n-1) -8*a(n-2) for n > 3.