A301902 Number of n X 3 0..1 arrays with every element equal to 0, 2 or 3 horizontally or antidiagonally adjacent elements, with upper left element zero.

1, 2, 3, 7, 16, 43, 117, 330, 935, 2667, 7616, 21775, 62273, 178130, 509563, 1457727, 4170224, 11930147, 34129757, 97638522, 279324735, 799093699, 2286051744, 6539949991, 18709526921, 53524323778, 153122698291, 438054310967

Offset: 1

Author

R. H. Hardin, Mar 28 2018

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 3 of A301906.

Formula

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