A301779 Number of nX3 0..1 arrays with every element equal to 0, 1, 2 or 3 horizontally or vertically adjacent elements, with upper left element zero.

4, 32, 240, 1808, 13616, 102544, 772272, 5816080, 43801648, 329875856, 2484337584, 18709866512, 140906415920, 1061184377488, 7991916306096, 60188151652624, 453284726792752, 3413745694159760, 25709358766289328, 193620494140664336

Offset

1,1

Comments

Column 3 of A301784.

Links

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

Formula

Empirical: a(n) = 7*a(n-1) +4*a(n-2)

Example

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

Crossrefs

Cf. A301784.

Sequence in context: A303451 A301438 A331334 * A370044 A147551 A316803

Adjacent sequences: A301776 A301777 A301778 * A301780 A301781 A301782

Keyword

nonn

Author

R. H. Hardin, Mar 26 2018

Status

approved