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A084100
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Expansion of (1+x-x^2-x^3)/(1+x^2).
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1
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1, 1, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2, -2, 2, 2, -2
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Partial sums are A084099.
The unsigned sequence 1,1,2,2,2,2,.. has g.f. (1+x^2)/(1-x) and a(n)=sum{k=0..n, binomial(1,k/2)(1+(-1)^k)/2}. Its partial sums are A004275(n+1). The sequence 1,-1,2,-2,2,-2,... has g.f. (1+x^2)/(1+x) and a(n)=sum{k=0..n, (-1)^(n-k)binomial(1,k/2)(1+(-1)^k)/2}. - Paul Barry (pbarry(AT)wit.ie), Oct 15 2004
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MATHEMATICA
| CoefficientList[Series[(1+x-x^2-x^3)/(1+x^2), {x, 0, 100}], x] (* From Harvey P. Dale, Apr 20 2011 *)
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CROSSREFS
| Sequence in context: A065687 A077433 A065685 * A130130 A046698 A007395
Adjacent sequences: A084097 A084098 A084099 * A084101 A084102 A084103
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KEYWORD
| easy,sign
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), May 15 2003
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