OFFSET
0,93
COMMENTS
|a(n)|<2 if n<92, |a(n)|<3 if n<204.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
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
KEYWORD
sign
AUTHOR
Michael Somos, Nov 06 2005
STATUS
approved