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A229581
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Number of defective 3-colorings of an n X 3 0..2 array connected horizontally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..2 order.
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1
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2, 28, 264, 2160, 16416, 119232, 839808, 5785344, 39191040, 262020096, 1733363712, 11367641088, 74010599424, 478892113920, 3082323787776, 19747769352192, 126009575866368, 801195213717504, 5077997833420800, 32092946307219456
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OFFSET
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1,1
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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) = 12*a(n-1) - 36*a(n-2).
Conjectures from Colin Barker, Sep 19 2018: (Start)
G.f.: 2*(1 + 2*x) / (1 - 6*x)^2.
a(n) = 2^(n + 1) * 3^(n - 1) * (4*n + 3).
(End)
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EXAMPLE
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Some solutions for n=3:
..0..1..1....0..1..2....0..0..1....0..1..2....0..1..2....0..1..2....0..1..0
..0..2..1....0..1..2....1..0..2....2..1..0....2..0..1....0..1..0....2..1..0
..0..2..1....0..2..0....2..1..0....2..2..0....2..2..1....0..1..1....2..2..0
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CROSSREFS
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Column 3 of A229586.
Sequence in context: A326248 A230270 A230759 * A230589 A097353 A092801
Adjacent sequences: A229578 A229579 A229580 * A229582 A229583 A229584
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Sep 26 2013
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STATUS
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approved
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