A259635 Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00000000 or 00000001.

18, 29, 69, 133, 236, 472, 940, 1781, 3433, 6725, 13008, 25088, 48696, 94445, 182717, 353893, 685924, 1328520, 2572916, 4984581, 9656065, 18703333, 36229992, 70182768, 135948832, 263342141, 510120437, 988149701, 1914124956, 3707828408

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(18 + 11*x + 40*x^2 + 10*x^3 - 2*x^4) / (1 - x - 3*x^3 - x^4). - Colin Barker, Dec 26 2018

Example

Some solutions for n=4:
..0..1..0....0..0..0....0..1..0....0..0..0....0..0..0....0..0..1....0..0..0
..0..1..0....0..0..0....0..1..0....0..0..0....0..1..0....0..0..0....0..0..1
..0..0..0....0..1..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0
..0..0..0....0..0..0....0..0..0....1..0..0....0..0..0....0..0..0....0..0..0
..0..1..0....0..0..0....0..1..0....0..0..0....0..0..0....0..0..0....0..0..0
..0..1..0....0..0..1....1..0..0....0..0..0....1..0..0....0..1..0....0..0..0

Crossrefs

Column 1 of A259642.

Sequence in context: A045000 A205871 A144833 * A366964 A032612 A151700

Adjacent sequences: A259632 A259633 A259634 * A259636 A259637 A259638

Keyword

nonn

Author

R. H. Hardin, Jul 02 2015

Status

approved