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A208068
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Number of n X 7 0..1 arrays avoiding 0 0 0 and 1 1 1 horizontally and 0 0 1 and 0 1 1 vertically.
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1
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42, 1764, 6216, 21904, 48840, 108900, 198000, 360000, 582000, 940900, 1408440, 2108304, 2988216, 4235364, 5762400, 7840000, 10332000, 13616100, 17490600, 22467600, 28259880, 35545444, 43928016, 54287424, 66090960, 80460900, 96696600
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OFFSET
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1,1
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COMMENTS
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Column 7 of A208069.
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..210
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FORMULA
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Empirical: a(n) = 2*a(n-1) + 4*a(n-2) - 10*a(n-3) - 5*a(n-4) + 20*a(n-5) - 20*a(n-7) + 5*a(n-8) + 10*a(n-9) - 4*a(n-10) - 2*a(n-11) + a(n-12) for n>13.
Empirical g.f.: 2*x*(21 + 840*x + 1260*x^2 + 1418*x^3 - 991*x^4 - 3128*x^5 - 160*x^6 + 1420*x^7 + 95*x^8 - 160*x^9 + 84*x^10 + 42*x^11 - 21*x^12) / ((1 - x)^7*(1 + x)^5). - Colin Barker, Jun 27 2018
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EXAMPLE
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Some solutions for n=4:
..1..1..0..0..1..1..0....1..0..1..0..1..0..1....0..0..1..0..1..1..0
..0..1..1..0..1..1..0....0..1..0..1..1..0..1....0..0..1..1..0..1..1
..0..1..0..0..1..1..0....0..0..1..0..1..0..1....0..0..1..0..0..1..0
..0..0..1..0..0..1..0....0..1..0..1..1..0..0....0..0..1..0..0..1..0
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CROSSREFS
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Cf. A208069.
Sequence in context: A207844 A206986 A208378 * A207933 A207850 A208839
Adjacent sequences: A208065 A208066 A208067 * A208069 A208070 A208071
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Feb 23 2012
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STATUS
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approved
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