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A174785
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Expansion of (1+2x-x^2+x^3-x^4-x^5)/(1+x^3)^2.
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1
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1, 2, -1, -1, -5, 1, 1, 8, -1, -1, -11, 1, 1, 14, -1, -1, -17, 1, 1, 20, -1, -1, -23, 1, 1, 26, -1, -1, -29, 1, 1, 32, -1, -1, -35, 1, 1, 38, -1, -1, -41, 1, 1, 44, -1, -1, -47, 1, 1, 50, -1
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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a(n)=(n+4)*cos(pi*n/3)/3+n*sin(pi*n/3)/sqrt(3)-(n+1)*(-1)^n/3.
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MATHEMATICA
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CoefficientList[Series[(1+2x-x^2+x^3-x^4-x^5)/(1+x^3)^2, {x, 0, 50}], x] (* or *) LinearRecurrence[{0, 0, -2, 0, 0, -1}, {1, 2, -1, -1, -5, 1}, 60] (* Harvey P. Dale, May 11 2019 *)
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CROSSREFS
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KEYWORD
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easy,sign
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AUTHOR
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STATUS
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approved
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