for k =1 , inner for loop iterates n times.
for k=2, inner for loop iterates n/2 times.
for k =3 , inner for loop iterates n/3 times.
......................
for k= n , inner for loop iterates n/n time.
so total = n+n/2+n/3+......n/n = n(1+1/2+1/3+....)=O(nlogn)