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A128016
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Expansion of (1+x+x^2+x^3)/(1-x^2+x^4).
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1
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1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1, 1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1, 1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1, 1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1, 1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1, 1, 1, 2, 2, 1, 1, -1, -1, -2, -2, -1, -1
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OFFSET
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0,3
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COMMENTS
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Periodic{1,1,2,2,1,1,-1,-1,-2,-2,-1,-1}.
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LINKS
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FORMULA
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G.f.: (1-x^4)/(1-x-x^2+x^3+x^4-x^5); a(n)=cos(5*pi*n/6)/2+(1-sqrt(3)/2)sin(5*pi*n/6)+cos(pi*n/6)/2+(1+sqrt(3)/2)sin(pi*n/6);
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MATHEMATICA
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CoefficientList[Series[(1+x+x^2+x^3)/(1-x^2+x^4), {x, 0, 100}], x] (* or *) LinearRecurrence[{0, 1, 0, -1}, {1, 1, 2, 2}, 100] (* Harvey P. Dale, Aug 02 2015 *)
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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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