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A301994
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Number of n X 3 0..1 arrays with every element equal to 1, 2 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.
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1
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1, 2, 5, 15, 48, 155, 499, 1602, 5137, 16467, 52784, 169199, 542375, 1738618, 5573261, 17865479, 57269040, 183579891, 588478091, 1886407378, 6047009817, 19384109803, 62137109808, 199184819687, 638500768991, 2046758546378, 6561026627701
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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) = 5*a(n-1) - 7*a(n-2) + 4*a(n-3).
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EXAMPLE
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Some solutions for n=5:
0 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 0 0 1
1 1 0 1 1 0 1 1 1 0 1 1 1 1 1 1 1 0 1 1 1
1 0 0 0 0 0 1 0 0 0 0 1 1 1 1 0 0 0 1 0 0
1 1 0 0 1 1 1 1 0 0 1 0 1 0 0 0 1 0 1 1 1
1 0 0 1 0 0 1 0 0 1 0 0 0 1 1 1 0 0 0 0 0
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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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