A301946 Number of nX3 0..1 arrays with every element equal to 1, 2 or 3 horizontally or antidiagonally adjacent elements, with upper left element zero.

1, 5, 20, 83, 342, 1411, 5820, 24007, 99026, 408471, 1684896, 6950003, 28667966, 118252075, 487776260, 2012021183, 8299356842, 34233896031, 141210898600, 582478776747, 2402658213526, 9910689833651, 40880459994636, 168627213385143

Offset: 1

Author

R. H. Hardin, Mar 29 2018

Keywords

• nonn

Comments

Column 3 of A301951.

Examples

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

Links

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

Crossrefs

Cf. A301951.

Formula

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