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A317817
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Number of nX2 0..1 arrays with every element unequal to 1, 2 or 3 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
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3
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1, 5, 16, 50, 160, 511, 1634, 5226, 16716, 53471, 171045, 547149, 1750258, 5598852, 17910021, 57291907, 183269625, 586256561, 1875361283, 5999045795, 19190195958, 61387032829, 196369427849, 628161199864, 2009408986694, 6427847623748
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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) -3*a(n-4) -2*a(n-5) -a(n-6)
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EXAMPLE
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Some solutions for n=5
..0..1. .0..1. .0..0. .0..1. .0..1. .0..0. .0..1. .0..0. .0..1. .0..1
..0..1. .0..0. .1..1. .0..1. .1..1. .1..1. .0..1. .1..0. .1..0. .1..1
..1..1. .1..0. .0..0. .0..0. .0..0. .0..1. .0..0. .1..0. .1..0. .1..0
..0..0. .1..0. .1..1. .1..1. .1..1. .0..0. .0..1. .0..0. .1..0. .0..1
..1..0. .1..0. .0..0. .0..1. .0..1. .0..1. .1..0. .0..1. .1..1. .0..1
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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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