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A110513
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Expansion of (1 + x)/(1 + 2x + x^3).
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4
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1, -1, 2, -5, 11, -24, 53, -117, 258, -569, 1255, -2768, 6105, -13465, 29698, -65501, 144467, -318632, 702765, -1549997, 3418626, -7540017, 16630031, -36678688, 80897393, -178424817, 393528322, -867954037, 1914332891, -4222194104, 9312342245, -20539017381, 45300228866, -99912799977
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OFFSET
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0,3
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COMMENTS
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LINKS
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FORMULA
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a(n) = Sum_{k=0..floor(n/2)} Sum_{j=0..(n-k)} (-1)^(n-k-j)*C(n-k, j)*(-2)^(j-k)*C(k, j-k).
a(0)=1, a(1)=-1, a(2)=2, a(n) = -2*a(n-1) - a(n-3). - Harvey P. Dale, Jun 27 2012
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MATHEMATICA
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CoefficientList[Series[(1+x)/(1+2x+x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[ {-2, 0, -1}, {1, -1, 2}, 40] (* Harvey P. Dale, Jun 27 2012 *)
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PROG
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(PARI) x='x+O('x^50); Vec((1+x)/(1+2x+x^3)) \\ G. C. Greubel, Aug 29 2017
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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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