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A302624
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Number of 3Xn 0..1 arrays with every element equal to 0, 1, 2 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
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1
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4, 25, 25, 45, 79, 146, 286, 563, 1114, 2222, 4435, 8858, 17710, 35411, 70810, 141614, 283219, 566426, 1132846, 2265683, 4531354, 9062702, 18125395, 36250778, 72501550, 145003091, 290006170, 580012334, 1160024659, 2320049306, 4640098606
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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-3) -2*a(n-4) for n>8
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EXAMPLE
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Some solutions for n=5
..0..1..0..1..1. .0..0..1..0..1. .0..1..1..0..1. .0..1..0..1..1
..0..1..0..1..0. .1..0..0..0..1. .0..0..1..0..1. .1..0..1..0..0
..1..1..0..1..1. .1..0..1..0..1. .1..0..1..0..0. .1..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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