OFFSET
0,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..438
FORMULA
E.g.f.: exp(Sum_{k>=1} A060648(k)*x^k/k).
MATHEMATICA
nmax = 20; CoefficientList[Series[Product[1/(1 - x^k)^(DirichletConvolve[j, MoebiusMu[j]^2, j, k]/k), {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
a[n_] := a[n] = Sum[Sum[2^PrimeNu[d]/d, {d, Divisors[k]}] k! Binomial[n - 1, k - 1] a[n - k], {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 20}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, May 27 2019
STATUS
approved