I liked this problem a lot :)

I searched after contest for a fast solution and I found an O(n^(2/3)) solution for it :)

This problem Is a famous problem and has a lot of github codes, He want the partial sum for prime omega function

But I liked this problem, because there is no pupil will know that problem is duplicated and this is a problem for a pupil :)

I searched after the contest but in the contest I didn't know that :o

If you like challenge you can try to solve it with O(n^(2/3)) solution here