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A229695
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Number of defective 3-colorings of a 2Xn 0..2 array connected horizontally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..2 order
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1
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0, 3, 43, 245, 1171, 5077, 20691, 80757, 305235, 1125333, 4067091, 14461173, 50723091, 175867605, 603736659, 2054728053, 6940088019, 23284024533, 77651501715, 257577229557, 850273182099, 2794463987157, 9147385165779
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 9*a(n-1) -27*a(n-2) +27*a(n-3) for n>6.
Empirical: G.f. 3*x^2+43*x^3 -x^4*(245-1034*x+1153*x^2) / (3*x-1)^3. - R. J. Mathar, Sep 29 2013
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EXAMPLE
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Some solutions for n=3
..0..1..1....0..1..1....0..1..2....0..1..0....0..0..1....0..1..0....0..0..1
..0..0..1....0..0..2....1..1..0....1..0..1....1..2..2....2..0..0....2..2..0
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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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