The outer loop runs n times.
For each iteration, the inner loops runs n / i times.
The total number of runs is:
n + n/2 + n/3 + ... + n/n
Asymptotically (ignoring integer arithmetic rounding), this simplifies as
n * (1 + 1/2 + 1/3 + ... + 1/n)
This series loosely converges towards n * log(n).
Hence the complexity is O(N.log(N)) as you expected.
