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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. 8
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified September 30 07:52 EDT 2022. Contains 357104 sequences. (Running on oeis4.)