OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
FORMULA
Expansion of eta(q^2)^6*eta(q^3)^4*eta(q^18)^2/(eta(q)^3*eta(q^6)^8*eta(q^9)) in powers of q.
Euler transform of period 18 sequence [ 3, -3, -1, -3, 3, 1, 3, -3, 0, -3, 3, 1, 3, -3, -1, -3, 3, 0, ...].
MATHEMATICA
eta[x_] := x^(1/24)*QPochhammer[x]; A122831[n_] := SeriesCoefficient[ eta[q^2]^6*eta[q^3]^4*eta[q^18]^2/(eta[q]^3*eta[q^6]^8*eta[q^9] ), {q, 0, n}]; Table[A122831[n], {n, 0, 50}] (* G. C. Greubel, Aug 17 2017 *)
PROG
(PARI) {a(n)=local(A); if(n<0, 0, A=x*O(x^n); polcoeff( eta(x^2+A)^6*eta(x^3+A)^4*eta(x^18+A)^2/eta(x+A)^3/eta(x^6+A)^8/eta(x^9+A), n))}
CROSSREFS
KEYWORD
sign
AUTHOR
Michael Somos, Sep 12 2006
STATUS
approved