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A232453
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Number of n X 2 0..2 arrays with every 0 next to a 1 and every 1 next to a 2 horizontally, vertically, diagonally or antidiagonally.
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1
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3, 51, 381, 3015, 24651, 198945, 1607067, 12991131, 104990445, 848511855, 6857610579, 55422433089, 447917887827, 3620023336611, 29256629564061, 236448855048951, 1910953595190267, 15444116384727393, 124817646797556651
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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) = 6*a(n-1) + 12*a(n-2) + 39*a(n-3).
Empirical g.f.: 3*x*(1 + 11*x + 13*x^2) / (1 - 6*x - 12*x^2 - 39*x^3). - Colin Barker, Oct 05 2018
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EXAMPLE
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Some solutions for n=6:
..1..0....1..1....0..2....0..2....1..1....0..1....1..0....0..1....0..2....1..1
..2..1....2..2....1..2....2..1....2..0....1..2....2..1....2..2....1..0....0..2
..1..0....1..2....1..2....1..0....2..2....1..0....2..2....2..2....0..0....0..2
..0..0....1..2....0..1....1..1....2..2....2..2....2..2....1..0....0..1....1..1
..0..1....2..1....1..2....2..0....1..2....0..2....1..2....0..2....1..2....2..1
..2..2....0..1....0..0....1..0....0..1....2..1....1..1....0..1....2..1....1..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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