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A303684
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Number of nX2 0..1 arrays with every element unequal to 2, 3 or 4 king-move adjacent elements, with upper left element zero.
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12
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0, 3, 5, 18, 61, 209, 702, 2381, 8069, 27330, 92581, 313641, 1062502, 3599373, 12193421, 41307034, 139933701, 474046225, 1605902110, 5440232205, 18429595637, 62432996082, 211501059173, 716491292025, 2427220807318, 8222571457613
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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) +2*a(n-3) -2*a(n-4) -4*a(n-5) for n>6
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EXAMPLE
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Some solutions for n=5
..0..1. .0..0. .0..0. .0..1. .0..1. .0..1. .0..0. .0..1. .0..1. .0..1
..0..1. .1..1. .1..1. .0..1. .1..0. .1..0. .1..1. .0..1. .1..0. .0..1
..0..0. .0..0. .1..0. .0..0. .0..1. .0..0. .0..1. .0..0. .1..0. .1..0
..1..0. .0..0. .0..0. .1..0. .0..1. .0..1. .0..1. .0..1. .1..1. .0..1
..0..1. .1..1. .1..1. .1..0. .0..1. .1..0. .1..0. .0..1. .0..0. .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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