A143241 Expansion of Product_{k>0} (1 - x^k) / (1 - x^(6*k - 2)).

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

Offset

0,104

Comments

|a(n)|<2 if n<103, |a(n)|<3 if n<161.

Links

Table of n, a(n) for n=0..104.

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: A374061 A374276 A037281 * A308064 A258825 A361162

Adjacent sequences: A143238 A143239 A143240 * A143242 A143243 A143244

Keyword

sign

Author

Michael Somos, Aug 01 2008

Status

approved