A300641 Number of nX3 0..1 arrays with every element equal to 2, 3, 4 or 5 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

0, 2, 2, 10, 30, 104, 340, 1144, 3795, 12683, 42227, 140876, 469517, 1565586, 5219130, 17400850, 58012053, 193409644, 644810491, 2149754855, 7167115016, 23894640479, 79662932803, 265590322328, 885458314722, 2952052210282, 9841922224851

Offset: 1

Author

R. H. Hardin, Mar 10 2018

Keywords

• nonn

Comments

Column 3 of A300646.

Examples

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

Links

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

Crossrefs

Cf. A300646.

Formula

Empirical: a(n) = 2*a(n-1) +4*a(n-2) -a(n-3) +7*a(n-4) +6*a(n-5) -2*a(n-6) -7*a(n-7) -11*a(n-8) -12*a(n-9) -8*a(n-10) -9*a(n-11) -3*a(n-12) -2*a(n-14) +a(n-15)