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A208377
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Number of n X 6 0..1 arrays avoiding 0 0 0 and 1 1 1 horizontally and 0 0 1 and 1 0 1 vertically.
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1
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26, 676, 2080, 4212, 7072, 10660, 14976, 20020, 25792, 32292, 39520, 47476, 56160, 65572, 75712, 86580, 98176, 110500, 123552, 137332, 151840, 167076, 183040, 199732, 217152, 235300, 254176, 273780, 294112, 315172, 336960, 359476, 382720
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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) = 364*n^2 - 416*n + 52 for n>1.
G.f.: 26*x*(1 + 23*x + 5*x^2 - x^3) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>4.
(End)
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EXAMPLE
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Some solutions for n=4:
..1..1..0..0..1..0....1..1..0..1..0..0....1..1..0..1..0..0....1..0..1..0..0..1
..1..1..0..0..1..0....1..1..0..1..1..0....0..1..1..0..1..0....0..0..1..1..0..1
..0..1..0..0..1..0....1..0..0..1..0..0....0..0..1..0..1..0....0..0..1..1..0..0
..0..1..0..0..1..0....1..0..0..1..0..0....0..0..1..0..1..0....0..0..1..1..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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