On sums of prime factors

We study the arithmetic function sopfr$(n)$ (OEIS A001414) which gives the sum of prime factors (with repetition) of a number $n$. In particular we obtain the asymptotic formula $$\sum _{n\le x}\mathrm{s}\mathrm{o}\mathrm{p}\mathrm{f}\mathrm{r}(n)\sim \frac{{\pi }^2}{12}\frac{x^2}{\log x},$$ which holds as well for the function sopf$(n)$ (OEIS A008472) that just gives the sum of distinct prime factors of $n$. This asymptotic formula was already stated by R. Jakimcyuk \cite{rj12} which was brought to our attention after the completion of the first version of this manuscript.