OFFSET
0,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..1000
FORMULA
a(n) ~ exp(2*Pi * (7*Zeta(3))^(1/4) * n^(3/4) / (3^(5/4) * 5^(1/4)) + sqrt(15*Zeta(3)*n/7)/4 - (5^(1/4) * 7^(3/4) * Pi / (3^(7/4) * Zeta(3)^(1/4)) + 15^(5/4) * Zeta(3)^(3/4) / (7^(5/4)*Pi)) * n^(1/4)/16 + 75*Zeta(3) / (784*Pi^2) + 5/192) * (7*Zeta(3))^(1/8) / (2^(95/48) * 15^(1/8) * n^(5/8)).
MATHEMATICA
nmax = 40; CoefficientList[Series[Exp[Sum[-(-1)^j * Sum[(DivisorSigma[1, k] + DivisorSigma[2, k]) * x^(j*k) / (2*j), {k, 1, Floor[nmax/j] + 1}], {j, 1, nmax}]], {x, 0, nmax}], x] (* Vaclav Kotesovec, Mar 31 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Mar 28 2018
STATUS
approved