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A111915
Expansion of -x^2*(x-1)*(x^2-x+1)*(x+x^2+1)/(1-x^4+x^8).
3
0, 0, 1, -1, 1, -1, 2, -2, 1, -1, 1, -1, 0, 0, -1, 1, -1, 1, -2, 2, -1, 1, -1, 1, 0, 0, 1, -1, 1, -1, 2, -2, 1, -1, 1, -1, 0, 0, -1, 1, -1, 1, -2, 2, -1, 1, -1, 1, 0, 0, 1, -1, 1, -1, 2, -2, 1, -1, 1, -1, 0, 0, -1, 1, -1, 1, -2, 2, -1, 1, -1, 1, 0, 0, 1, -1, 1, -1, 2, -2, 1, -1, 1, -1, 0, 0, -1, 1, -1, 1, -2, 2, -1, 1, -1, 1, 0, 0, 1, -1
OFFSET
0,7
COMMENTS
It appears that a(n) has period 24.
This is true, as (1-x^4+x^8) is the cyclotomic polynomial for n=24. - Joerg Arndt, Feb 03 2017
FORMULA
G.f.: -x^2*(x-1)*(x^2-x+1)*(x+x^2+1)/(1-x^4+x^8).
MATHEMATICA
CoefficientList[Series[-x^2*(x - 1)*(x^2 - x + 1)*(x + x^2 + 1)/(1 - x^4 + x^8), {x, 0, 100}], x] (* Wesley Ivan Hurt, Feb 03 2017 *)
PROG
(PARI) a(n)=[0, 0, 1, -1, 1, -1, 2, -2, 1, -1, 1, -1, 0, 0, -1, 1, -1, 1, -2, 2, -1, 1, -1, 1][n%24+1] \\ Charles R Greathouse IV, Feb 03 2017
CROSSREFS
KEYWORD
easy,less,sign
AUTHOR
Creighton Dement, Aug 20 2005
STATUS
approved