The mean of first n natural numbers =
n/2
(n+1)/2
n(n-1)/2
(2n+1)/2
The mean of any n observations= sum of all the observations/n
So, in this case
Mean = {n(n+1)/2}/n
= (n+1)/2
The harmonic mean of sum of first n natural numbers and sum of cubes of first n natural numbers is