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A122434
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Expansion of (1+x)^3/(1+x+x^2).
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1
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1, 2, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0, -1, 1, 0
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OFFSET
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0,2
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COMMENTS
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Row sums of number triangle A122433. Binomial transform is A077859.
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LINKS
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Table of n, a(n) for n=0..68.
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FORMULA
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a(n)=2*sqrt(3)*cos(2*pi*n/3+pi/6)/3+C(1,n)+C(0,n)
a(n) = -A049347(n) if n>=2 . - R. J. Mathar, Feb 08 2008
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MATHEMATICA
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CoefficientList[Series[(1+x)^3/(1+x+x^2), {x, 0, 70}], x] (* or *) PadRight[ {1, 2, 0}, 71, {-1, 1, 0}] (* From Harvey P. Dale, Apr 25 2012 *)
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CROSSREFS
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Sequence in context: A116377 A131964 A065339 * A141571 A164067 A113706
Adjacent sequences: A122431 A122432 A122433 * A122435 A122436 A122437
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KEYWORD
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easy,sign
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AUTHOR
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Paul Barry, Sep 04 2006
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STATUS
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approved
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