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A316688
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Number of nX3 0..1 arrays with every element unequal to 0, 1, 2, 6, 7 or 8 king-move adjacent elements, with upper left element zero.
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1
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4, 3, 8, 9, 21, 42, 81, 165, 330, 657, 1317, 2634, 5265, 10533, 21066, 42129, 84261, 168522, 337041, 674085, 1348170, 2696337, 5392677, 10785354, 21570705, 43141413, 86282826, 172565649, 345131301, 690262602, 1380525201, 2761050405, 5522100810
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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) = a(n-1) +a(n-2) +2*a(n-3) for n>6
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EXAMPLE
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Some solutions for n=5
..0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0
..0..0..0. .0..0..0. .0..1..0. .0..0..0. .0..1..0. .0..0..0. .0..0..0
..0..1..0. .0..1..0. .1..0..1. .0..0..0. .0..0..0. .0..1..0. .0..0..0
..0..0..0. .0..1..0. .1..1..1. .0..1..0. .0..1..0. .1..0..1. .0..1..0
..0..0..0. .0..0..0. .1..1..1. .1..0..0. .1..0..0. .1..1..1. .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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