A303677 Number of nX2 0..1 arrays with every element unequal to 0, 1 or 3 king-move adjacent elements, with upper left element zero.

2, 5, 7, 17, 31, 49, 103, 193, 327, 641, 1207, 2129, 4039, 7585, 13687, 25585, 47847, 87425, 162391, 302609, 556615, 1031329, 1916983, 3538225, 6550311, 12155585, 22474519, 41599313, 77121031, 142707937, 264156151, 489441649, 906031335

Offset: 1

Author

R. H. Hardin, Apr 28 2018

Keywords

• nonn

Comments

Column 2 of A303682.

Examples

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

Links

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

Crossrefs

Cf. A303682.

Formula

Empirical: a(n) = a(n-1) +4*a(n-3) -2*a(n-4) for n>5