A303721 Number of nX2 0..1 arrays with every element unequal to 0, 1, 2 or 3 king-move adjacent elements, with upper left element zero.

2, 8, 21, 49, 120, 293, 719, 1774, 4389, 10893, 27096, 67529, 168555, 421238, 1053769, 2638209, 6609224, 16565853, 41538871, 104192734, 261416765, 656024133, 1646562744, 4133274369, 10376622259, 26052793638, 65415654721, 164260171289

Offset

1,1

Comments

Column 2 of A303727.

Links

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

Formula

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

Example

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

Crossrefs

Cf. A303727.

Sequence in context: A000160 A034519 A014409 * A109782 A237268 A216893

Adjacent sequences: A303718 A303719 A303720 * A303722 A303723 A303724

Keyword

nonn

Author

R. H. Hardin, Apr 29 2018

Status

approved