Let $\sum_{n=1}^{\infty} a_n$ be a divergent series of positive terms and $\{s_n\}_{n=1}^{\infty}$ denote the sequence of it's partial sums. Test the convergence of the series $\sum_{n=1}^{\infty} \frac{a_n}{s_n}$.
Attempt: Since $\sum_{n=1}^{\infty} a_n$ be a divergent series of positive terms, $\{s_n\}_{n=1}^{\infty}$ is unbounded.what to next, I have no idea, So I need help.
Thank you.