A301995 Number of nX4 0..1 arrays with every element equal to 1, 2 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.

2, 8, 26, 74, 200, 530, 1394, 3656, 9578, 25082, 65672, 171938, 450146, 1178504, 3085370, 8077610, 21147464, 55364786, 144946898, 379475912, 993480842, 2600966618, 6809419016, 17827290434, 46672452290, 122190066440, 319897747034

Offset: 1

Author

R. H. Hardin, Mar 30 2018

Keywords

• nonn

Comments

Column 4 of A301999.

Examples

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

Links

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

Crossrefs

Cf. A301999.

Formula

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