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A232251
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Number of (n+1) X (2+1) 0..2 arrays with every element both >= and <= some horizontal or antidiagonal neighbor.
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2
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37, 421, 4711, 52779, 591181, 6622029, 74175439, 830862931, 9306762101, 104248027381, 1167715590199, 13079956849787, 146512791834269, 1641136772671133, 18382899355702175, 205912751666562211
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 10*a(n-1) + 14*a(n-2) - 6*a(n-3) - a(n-4).
Empirical g.f.: x*(37 + 51*x - 17*x^2 - 3*x^3) / (1 - 10*x - 14*x^2 + 6*x^3 + x^4). - Colin Barker, Oct 03 2018
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EXAMPLE
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Some solutions for n=4:
..0..0..2....0..0..0....2..2..2....0..0..0....0..0..1....2..2..0....0..0..2
..0..2..1....0..0..2....0..0..0....1..2..1....1..2..2....0..0..1....0..2..2
..2..1..1....1..2..0....0..0..0....2..1..1....2..1..0....1..2..2....2..2..1
..1..2..1....2..0..0....1..2..2....1..0..0....0..0..2....0..0..1....0..0..1
..2..0..0....0..2..2....2..2..2....0..2..2....0..2..2....1..1..1....0..2..2
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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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