OFFSET
0,2
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..10000
B. Gordon and R. J. McIntosh, Some eighth order mock theta functions, J. London Math. Soc. 62 (2000), 321-335.
FORMULA
V_0(q) = -1 + 2*Sum_{n >= 0} q^(n^2)(1+q)(1+q^3)...(1+q^(2n-1))/((1-q)(1-q^3)...(1-q^(2n-1))).
a(n) ~ exp(Pi*sqrt(n)/2) / (2*sqrt(n)). - Vaclav Kotesovec, Jun 12 2019
MATHEMATICA
nmax = 100; CoefficientList[Series[-1 + 2*Sum[x^(k^2) * Product[(1 + x^(2*j - 1))/(1 - x^(2*j - 1)), {j, 1, k}], {k, 0, Floor[Sqrt[nmax]]}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Jun 12 2019 *)
PROG
(PARI) lista(nn) = my(q = qq + O(qq^nn)); gf = -1 + 2* sum(n = 0, nn, q^(n^2) * prod(k = 1, n, 1 + q^(2*k-1)) / prod(k = 1, n, 1 - q^(2*k-1))); Vec(gf) \\ Michel Marcus, Jun 18 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Jeremy Lovejoy, Dec 20 2008
EXTENSIONS
More terms from Michel Marcus, Feb 23 2015
STATUS
approved