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A277653
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Number of n X 2 0..2 arrays with every element equal to some element at offset (-1,0) (-1,1) (0,-1) (0,1) or (1,0) both plus 1 mod 3 and minus 1 mod 3, with new values introduced in order 0..2.
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1
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0, 0, 1, 2, 8, 28, 98, 346, 1218, 4290, 15110, 53218, 187438, 660170, 2325166, 8189402, 28843662, 101589450, 357805342, 1260216122, 4438571726, 15632968522, 55060438334, 193926819802, 683024192622, 2405660280426, 8472908349854
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OFFSET
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1,4
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LINKS
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FORMULA
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Empirical: a(n) = 3*a(n-1) + 2*a(n-2) - 2*a(n-4).
Empirical g.f.: x^3*(1 - x) / (1 - 3*x - 2*x^2 + 2*x^4). - Colin Barker, Feb 05 2019
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EXAMPLE
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All solutions for n=4:
..0..1. .0..1
..2..2. .2..2
..1..0. .1..0
..1..2. .2..1
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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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