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A229753
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Number of defective 4-colorings of an n X 6 0..3 array connected horizontally, vertically, diagonally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..3 order.
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1
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50, 6456, 17404, 32548, 57677, 102271, 186396, 354509, 704530, 1450667, 3059672, 6544921, 14099310, 30453719, 65785684, 141933029, 305639306, 656732227, 1407958032, 3011810033, 6428914918, 13695082991, 29117602316, 61795491133
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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) = 9*a(n-1) - 33*a(n-2) + 63*a(n-3) - 66*a(n-4) + 36*a(n-5) - 8*a(n-6) for n>11.
Empirical g.f.: x*(50 + 6006*x - 39050*x^2 + 85810*x^3 - 64351*x^4 - 14894*x^5 + 35422*x^6 - 8491*x^7 - 3870*x^8 - 356*x^9 + 888*x^10) / ((1 - x)^3*(1 - 2*x)^3). - Colin Barker, Sep 21 2018
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EXAMPLE
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Some solutions for n=3:
..0..1..2..3..0..2....0..1..2..3..0..1....0..1..0..2..0..2....0..1..0..2..1..0
..2..3..0..1..1..3....2..3..0..1..2..3....3..2..3..1..0..1....0..2..3..2..3..2
..1..0..2..3..0..2....2..1..2..3..0..2....1..0..1..2..3..2....3..1..0..1..0..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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