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A302266
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Number of 2Xn 0..1 arrays with every element equal to 0, 1, 2 or 3 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
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4
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2, 8, 29, 105, 384, 1405, 5135, 18766, 68589, 250693, 916272, 3348929, 12240187, 44737350, 163513041, 597632937, 2184322000, 7983600501, 29179707415, 106650542494, 389803024901, 1424712848861, 5207262571120, 19032314831801
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OFFSET
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1,1
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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) +4*a(n-3) +4*a(n-4)
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EXAMPLE
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Some solutions for n=5
..0..0..1..1..0. .0..0..1..0..1. .0..0..0..0..1. .0..0..1..0..1
..0..0..1..1..0. .0..0..1..1..0. .0..0..1..1..1. .0..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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