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A112215
McKay-Thompson series of class 90b for the Monster group.
3
1, -1, 0, 0, 0, 0, 0, -1, 1, 0, 0, -1, 1, -1, 1, 0, 0, -1, 2, -2, 2, -1, 0, -1, 3, -2, 1, -1, 1, -2, 4, -5, 3, -1, 1, -2, 4, -6, 4, -2, 3, -5, 6, -7, 6, -2, 1, -6, 10, -10, 9, -6, 4, -7, 12, -12, 9, -7, 6, -10, 18, -20, 13, -8, 9, -12, 18, -24, 20, -12, 13, -21, 27, -29, 24, -14, 13, -25, 36, -38, 35, -25, 19, -30, 46, -46, 36
OFFSET
0,19
LINKS
D. Ford, J. McKay and S. P. Norton, More on replicable functions, Commun. Algebra 22, No. 13, 5175-5193 (1994).
FORMULA
Expansion of q^(1/3)*(eta(q)*eta(q^6)*eta(q^10)*eta(q^15))/(eta(q^2) *eta(q^3)*eta(q^5)*eta(q^30)) in powers of q. - G. C. Greubel, Jun 06 2018
a(n) ~ (-1)^n * exp(2*Pi*sqrt(n/5)/3) / (2 * sqrt(3) * 5^(1/4) * n^(3/4)). - Vaclav Kotesovec, Jun 29 2018
EXAMPLE
T90b = 1/q - q^2 - q^20 + q^23 - q^32 + q^35 - q^38 + q^41 - q^50 + ...
MATHEMATICA
eta[q_]:= q^(1/24)*QPochhammer[q]; a[n_]:= SeriesCoefficient[q^(1/3)* (eta[q]*eta[q^6]*eta[q^10]*eta[q^15])/(eta[q^2]*eta[q^3]*eta[q^5]* eta[q^30]), {q, 0, n}]; Table[a[n], {n, 0, 50}] (* G. C. Greubel, Mar 04 2018 *)
nmax = 100; CoefficientList[Series[Product[(1 - x^(2*k - 1))*(1 - x^(30*k - 15))/((1 - x^(6*k - 3))*(1 - x^(10*k - 5))), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Jun 29 2018 *)
PROG
(PARI) q='q+O('q^80); F=(eta(q)*eta(q^6)*eta(q^10)*eta(q^15))/(eta(q^2) *eta(q^3)*eta(q^5)*eta(q^30)); Vec(F) \\ G. C. Greubel, Jun 06 2018
CROSSREFS
Sequence in context: A112211 A246575 A357563 * A176389 A076451 A230536
KEYWORD
sign
AUTHOR
Michael Somos, Aug 28 2005
STATUS
approved