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A303632
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Number of nX4 0..1 arrays with every element unequal to 2 or 3 horizontally or vertically adjacent elements, with upper left element zero.
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1
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0, 2, 1, 4, 8, 22, 47, 123, 302, 784, 1961, 5002, 12715, 32486, 82753, 211121, 538371, 1373975, 3505385, 8944576, 22822438, 58237614, 148606194, 379208575, 967645940, 2469221128, 6300909758, 16078584921, 41029120473, 104697723446, 267166736204
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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) -5*a(n-3) +a(n-4) -4*a(n-5) -9*a(n-6) -a(n-7) +39*a(n-8) -5*a(n-9) -26*a(n-10) +22*a(n-11) -a(n-12) +a(n-13) -8*a(n-14) -a(n-15) +2*a(n-16)
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EXAMPLE
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Some solutions for n=5
..0..1..1..0. .0..1..1..0. .0..1..1..0. .0..1..0..1. .0..1..0..1
..1..0..0..1. .1..0..0..1. .1..0..0..1. .1..1..0..0. .1..1..0..0
..0..1..1..0. .1..0..0..1. .0..1..0..1. .0..0..1..1. .0..0..1..1
..1..0..0..1. .0..1..1..0. .0..1..1..0. .1..0..1..0. .1..1..0..0
..0..1..1..0. .1..0..0..1. .1..0..0..1. .0..1..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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