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A229577
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Number of defective 4-colorings of an n X 7 0..3 array connected horizontally, vertically, diagonally and antidiagonally with exactly one mistake, and colors introduced in row-major 0..3 order.
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1
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246, 1312, 1584, 2064, 2852, 4048, 6108, 9992, 17716, 33504, 66188, 134200, 275940, 571280, 1186108, 2464488, 5119124, 10624576, 22028268, 45621656, 94380868, 195044592, 402663068, 830482504, 1711286772, 3523226528, 7247768908
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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) - 13*a(n-2) + 12*a(n-3) - 4*a(n-4) for n>7.
Empirical g.f.: 2*x*(123 - 82*x - 1545*x^2 + 3332*x^3 - 1850*x^4 + 4*x^5 + 232*x^6) / ((1 - x)^2*(1 - 2*x)^2). - Colin Barker, Sep 19 2018
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EXAMPLE
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Some solutions for n=3:
..0..1..2..1..2..1..0....0..1..0..2..3..1..0....0..1..2..1..2..1..2
..3..3..0..3..0..3..2....3..2..3..1..0..2..3....0..3..0..3..0..3..0
..2..1..2..1..2..1..0....0..1..0..2..3..2..0....2..1..2..1..2..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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