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A183814
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1/81 the number of (n+1) X 4 0..2 arrays with no 2 X 2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor.
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1
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64, 3256, 163208, 8231592, 414246824, 20864057480, 1050517114472, 52900274426120, 2663752907479720, 134133403972622152, 6754253376412941416, 340109468142471752968, 17126149629153540430376, 862384378029691966195144
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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) = 43*a(n-1) + 560*a(n-2) - 10054*a(n-3) + 24480*a(n-4) + 45920*a(n-5).
Empirical g.f.: 8*x*(8 + 63*x - 1580*x^2 + 4218*x^3 + 7624*x^4) / (1 - 43*x - 560*x^2 + 10054*x^3 - 24480*x^4 - 45920*x^5). - Colin Barker, Apr 04 2018
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EXAMPLE
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Some solutions with upper left block zero for 3 X 4:
..0..0..0..1....0..0..0..1....0..0..0..2....0..0..2..2....0..0..0..2
..0..0..1..1....0..0..1..2....0..0..1..1....0..0..1..0....0..0..2..0
..2..1..1..1....2..0..2..1....2..2..2..1....2..0..0..1....0..2..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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