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A222778
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Number of n X 3 0..6 arrays with no element equal to another at a city block distance of exactly two, and new values 0..6 introduced in row major order.
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1
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3, 34, 969, 64752, 5227536, 436214328, 36601614264, 3073970725512, 258205634457816, 21689162608860168, 1821888109561493784, 153038579509053600072, 12855240375043076417496, 1079840187251574876131208
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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) = 101*a(n-1) - 1470*a(n-2) + 3528*a(n-3) for n>5.
Empirical g.f.: x*(3 - 269*x + 1945*x^2 + 6279*x^3 - 7938*x^4) / ((1 - 3*x)*(1 - 14*x)*(1 - 84*x)). - Colin Barker, Aug 16 2018
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EXAMPLE
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Some solutions for n=3:
..0..1..2....0..1..2....0..1..2....0..1..1....0..1..2....0..1..2....0..1..2
..3..4..2....3..3..0....3..3..4....0..2..3....3..1..4....2..1..3....0..3..4
..2..5..0....4..2..0....1..0..4....1..4..0....5..0..4....4..5..3....1..2..4
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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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