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A318039
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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.
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1
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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
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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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
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EXAMPLE
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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
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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