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A303422
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Number of 3Xn 0..1 arrays with every element equal to 0, 1, 2, 3, 4 or 5 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
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1
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4, 32, 252, 1985, 15647, 123337, 972168, 7662841, 60400282, 476088932, 3752642337, 29579189147, 233149966025, 1837741608616, 14485501658565, 114178052735590, 899977648952776, 7093830637396745, 55915203194889879, 440736480491065049
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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) = 7*a(n-1) +4*a(n-2) +21*a(n-3) +18*a(n-4)
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EXAMPLE
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Some solutions for n=5
..0..1..1..1..1. .0..0..0..0..1. .0..0..0..0..0. .0..0..1..0..1
..1..1..0..1..0. .1..1..0..0..0. .0..1..0..1..1. .0..1..0..0..0
..1..0..0..1..0. .1..1..0..1..0. .1..0..0..1..0. .1..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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