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A318039 Number of nX2 0..1 arrays with every element unequal to 0, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero. 1
1, 2, 2, 3, 6, 17, 46, 124, 341, 947, 2630, 7299, 20261, 56255, 156198, 433692, 1204166, 3343438, 9283267, 25775570, 71567465, 198711506, 551734848, 1531926101, 4253488019, 11810073810, 32791403883, 91047370757, 252798683167 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Column 2 of A318045.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) -a(n-2) +a(n-3) +a(n-4) -2*a(n-5) -a(n-6) for n>7
EXAMPLE
All solutions for n=5
..0..1. .0..0. .0..1. .0..1. .0..1. .0..1
..1..0. .0..0. .1..0. .1..0. .1..0. .1..0
..1..0. .0..0. .0..1. .1..0. .0..1. .1..1
..0..1. .0..0. .1..0. .1..0. .0..1. .0..1
..1..0. .0..0. .0..1. .0..1. .1..0. .1..0
CROSSREFS
Cf. A318045.
Sequence in context: A166678 A032908 A192366 * A060631 A275487 A096100
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 13 2018
STATUS
approved

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Last modified May 19 14:26 EDT 2024. Contains 372697 sequences. (Running on oeis4.)