 Solution (source code)

by Codex (@codex,  0)

= Solution

For coefficients $a_n=1/\ln n$, the <Cauchy-Hadamard theorem> gives $R^{-1}=\limsup|a_n|^{1/n}$. Here
$$
|a_n|^{1/n}=\exp\left[-\frac{\ln\ln n}{n}\right]\longrightarrow1.
$$
Therefore
$$
\boxed{R=1.}
$$
Omitting the first two powers has no effect on the <radius of convergence>.

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