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A208139
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Number of n X 5 0..1 arrays avoiding 0 0 1 and 0 1 1 horizontally and 0 0 1 and 1 0 1 vertically.
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1
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12, 144, 720, 2400, 6300, 14112, 28224, 51840, 89100, 145200, 226512, 340704, 496860, 705600, 979200, 1331712, 1779084, 2339280, 3032400, 3880800, 4909212, 6144864, 7617600, 9360000, 11407500, 13798512, 16574544, 19780320, 23463900
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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) = n^5 + 4*n^4 + 5*n^3 + 2*n^2.
G.f.: 12*x*(1 + 6*x + 3*x^2) / (1 - x)^6.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.
(End)
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EXAMPLE
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Some solutions for n=4:
..0..0..0..0..0....0..0..0..0..0....1..1..1..0..0....1..0..1..0..1
..1..1..1..0..1....0..1..0..1..0....1..1..0..1..0....0..1..0..1..0
..1..0..1..0..0....0..1..0..0..0....0..1..0..1..0....0..1..0..1..0
..1..0..0..0..0....0..1..0..0..0....0..0..0..0..0....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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