A302146 Number of nX3 0..1 arrays with every element equal to 0, 2, 3 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.

1, 2, 4, 10, 28, 84, 260, 816, 2576, 8152, 25824, 81840, 259408, 822304, 2606720, 8263456, 26195776, 83042752, 263252544, 834533120, 2645541888, 8386596224, 26586234880, 84280663296, 267176990976, 846974167552, 2684981361664

Offset: 1

Author

R. H. Hardin, Apr 02 2018

Keywords

• nonn

Comments

Column 3 of A302150.

Examples

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

Links

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

Crossrefs

Cf. A302150.

Formula

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