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A259635 Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00000000 or 00000001. 1
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 (list; graph; refs; listen; history; text; internal format)
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 * A032612 A151700 A154367

Adjacent sequences:  A259632 A259633 A259634 * A259636 A259637 A259638

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jul 02 2015

STATUS

approved

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Last modified October 15 03:28 EDT 2019. Contains 328025 sequences. (Running on oeis4.)