Are there results, or can someone point me to reading, on computations of the following: $\lim_n \sum_{2 \le x\le n} e^{i \cdot \pi\cdot \log \log x }$ It would seem that there is reason to believe this should be something like $-\log(n)$. For example, see the graphic on [this question][1] which is the visual representation of $\sum_x (-1)^{\omega(x)}$ which for large $x$ is like $\sum_x (-1)^{\log \log (x)} = \sum_x e^{i \cdot \pi\cdot \log \log x }$. From the picture expectation, this looks something like $- \log n$. I dont know where to start, sources would be nice, thank you! [1]: https://math.stackexchange.com/questions/315775/on-the-number-of-integers-with-an-even-number-of-distinct-prime-factors/3303295#3303295