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A164118
Expansion of (1 - x^2) * (1 - x^4) * (1 - x^5) / ((1 - x) * (1 - x^10)) in powers of x.
2
1, 1, 0, 0, -1, -2, -1, 0, 0, 1, 2, 1, 0, 0, -1, -2, -1, 0, 0, 1, 2, 1, 0, 0, -1, -2, -1, 0, 0, 1, 2, 1, 0, 0, -1, -2, -1, 0, 0, 1, 2, 1, 0, 0, -1, -2, -1, 0, 0, 1, 2, 1, 0, 0, -1, -2, -1, 0, 0, 1, 2, 1, 0, 0, -1, -2, -1, 0, 0, 1, 2, 1, 0, 0, -1, -2, -1, 0, 0, 1, 2, 1, 0, 0, -1, -2, -1, 0, 0, 1, 2, 1, 0, 0, -1, -2, -1, 0, 0, 1, 2, 1, 0, 0, -1
OFFSET
0,6
FORMULA
Euler transform of length 10 sequence [ 1, -1, 0, -1, -1, 0, 0, 0, 0, 1].
a(-n) = a(n). a(n + 5) = -a(n) unless n=0 or n=-5.
G.f.: (1 - x^4) / (1 - x + x^2 - x^3 + x^4).
MATHEMATICA
CoefficientList[Series[(1 - x^4) / (1 - x + x^2 - x^3 + x^4), {x, 0, 50}], x] (* G. C. Greubel, Sep 12 2017 *)
PROG
(PARI) {a(n) = -(n==0) + [2, 1, 0, 0, -1, -2, -1, 0, 0, 1][n%10 + 1]}
CROSSREFS
A164116(n) = (-1)^n * a(n). Convolution inverse of A164117.
Sequence in context: A059048 A257181 A164116 * A180981 A284317 A281243
KEYWORD
sign,easy
AUTHOR
Michael Somos, Aug 10 2009
STATUS
approved