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A113706
Expansion of Product_{k>0} (1-x^(3k))/(1-x^(3k-2)).
2
1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, -1, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, -1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, -1, 1, 1, -1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, -1, 0, 0, 0, 1, 1, 0, 1, 0, -1, 1, 1, -1, 0, 1, -1, 0, 2, 0, -1, 1, 0, -1, 1, 1, 0, 1, 0, -1, 1
OFFSET
0,93
COMMENTS
|a(n)|<2 if n<92, |a(n)|<3 if n<204.
LINKS
FORMULA
Euler transform of period 3 sequence [1, 0, -1, ...].
G.f.: Product_{k>0} (1-x^(3k))/(1-x^(3k-2)).
PROG
(PARI) {a(n)=if(n<0, 0, polcoeff( prod(k=1, n, (1-x^k)^([1, -1, 0][k%3+1]), 1+x*O(x^n)), n))}
CROSSREFS
Cf. A143240.
Sequence in context: A305490 A374060 A375149 * A279952 A054845 A317991
KEYWORD
sign
AUTHOR
Michael Somos, Nov 06 2005
STATUS
approved