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A301965
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Number of 3Xn 0..1 arrays with every element equal to 0, 1 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.
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1
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4, 13, 16, 25, 41, 74, 132, 239, 437, 800, 1468, 2697, 4957, 9114, 16760, 30823, 56689, 104264, 191768, 352713, 648737, 1193210, 2194652, 4036591, 7424445, 13655680, 25116708, 46196825, 84969205, 156282730, 287448752, 528700679, 972432153
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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) = 2*a(n-1) -a(n-4) for n>6
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EXAMPLE
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Some solutions for n=5
..0..0..1..1..0. .0..1..0..1..0. .0..0..1..1..0. .0..1..0..0..1
..1..0..0..1..0. .0..0..0..1..1. .1..0..0..1..1. .0..1..1..0..1
..1..1..0..1..1. .0..1..0..0..1. .1..1..0..0..1. .0..0..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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