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A229665
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Number of defective 4-colorings of an nX1 0..3 array connected horizontally, antidiagonally and vertically with exactly two mistakes, and colors introduced in row-major 0..3 order
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2
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0, 0, 1, 3, 12, 50, 210, 861, 3416, 13140, 49230, 180455, 649572, 2302950, 8060234, 27900705, 95659440, 325241960, 1097691462, 3680494731, 12268315580, 40679151450, 134241199554, 441078226853, 1443528742152, 4707158941500
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OFFSET
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1,4
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 12*a(n-1) -57*a(n-2) +136*a(n-3) -171*a(n-4) +108*a(n-5) -27*a(n-6) for n>9.
Empirical: g.f. x^3 -x^4*(-3+24*x-77*x^2+114*x^3-72*x^4+18*x^5) / ( (3*x-1)^3*(x-1)^3 ). - R. J. Mathar, Sep 29 2013
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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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