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 A143241 Expansion of Product_{k>0} (1 - x^k) / (1 - x^(6*k - 2)). 0
 1, -1, -1, 0, 1, 0, -1, 1, 1, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, 1, 0, -1, 0, 0, 0, 1, 1, -1, 0, 1, 0, 0, 0, -1, -1, 1, 1, 0, 0, -1, 0, 1, 0, -1, -1, 0, 0, 1, 0, -1, 0, 0, 0, 1, 0, -1, 0, 1, 0, 0, 1, -1, -1, 1, 0, 1, 0, -1, -1, 1, 1, -1, 1, 0, -1, 1, 1, 0, -1, -1, -1, 1, 1, -1, -1, 0, 0, 1, 1, -1, -1, 0, 0, 1, 1, -1, -1, 0, 0, 1, 1, -1, -2, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,104 COMMENTS |a(n)|<2 if n<103, |a(n)|<3 if n<161. LINKS FORMULA Euler transform of period 6 sequence [ -1, -1, -1, 0, -1, -1, ...]. G.f.: Product_{k>0} (1 - x^k) / (1 - x^(6*k - 2)). EXAMPLE 1 - q - q^2 + q^4 - q^6 + q^7 + q^8 - q^12 - q^18 + q^20 - q^22 + ... PROG (PARI) {a(n) = if( n<0, 0, polcoeff( prod(k=1, n, (1 - x^k)^([1, 1, 1, 1, 0, 1][k%6 + 1]), 1 + x * O(x^n)), n))} CROSSREFS Sequence in context: A137979 A160338 A037281 * A118626 A062892 A118553 Adjacent sequences:  A143238 A143239 A143240 * A143242 A143243 A143244 KEYWORD sign AUTHOR Michael Somos, Aug 01 2008 STATUS approved

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