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

1,1

Comments

Column 2 of A303682.

Links

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

Formula

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

Example

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

Crossrefs

Cf. A303682.

Sequence in context: A142341 A318731 A256062 * A303802 A045357 A168035

Adjacent sequences: A303674 A303675 A303676 * A303678 A303679 A303680

Keyword

nonn

Author

R. H. Hardin, Apr 28 2018

Status

approved