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A306483
Expansion of Product_{k>=1} 1/(1 - psi(k)*x^k), where psi() is the Dedekind psi function (A001615).
1
1, 1, 4, 8, 23, 41, 114, 200, 491, 909, 2036, 3710, 8235, 14743, 31058, 56538, 115435, 207401, 417876, 745578, 1470371, 2626489, 5086108, 9030162, 17347019, 30620651, 58060380, 102426652, 192288399, 337633825, 629845430, 1101958752, 2040109199, 3563507377, 6553539316, 11412799294
OFFSET
0,3
LINKS
FORMULA
G.f.: exp(Sum_{k>=1} Sum_{j>=1} psi(j)^k*x^(j*k)/k).
From Vaclav Kotesovec, Feb 23 2019: (Start)
a(n) ~ c * 3^(n/2), where
c = 84.0923381459819921541124348082985... if n is even and
c = 82.6952907990079575265849718772977... if n is odd. (End)
MATHEMATICA
nmax = 35; CoefficientList[Series[Product[1/(1 - DirichletConvolve[i, MoebiusMu[i]^2, i, k] x^k), {k, 1, nmax}], {x, 0, nmax}], x]
nmax = 35; CoefficientList[Series[Exp[Sum[Sum[DirichletConvolve[i, MoebiusMu[i]^2, i, j]^k x^(j k)/k, {j, 1, nmax}], {k, 1, nmax}]], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d DirichletConvolve[i, MoebiusMu[i]^2, i, d]^(k/d), {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 35}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 18 2019
STATUS
approved