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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
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 29 2018
STATUS
approved

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Last modified July 13 04:46 EDT 2024. Contains 374267 sequences. (Running on oeis4.)