lol no, this is a bonus question and your equation does work.. I saw a simpler one on yahoo answer with the same right side of the equation but with out the left... Do you know how we can conclude this equation from several calculations?
and, how about if we a have a cubic power series?
Edit: I found out the equation for the cubic power series and is as follows, Sum = ((n(n+1))/2)^2
You could have found this webpage for yourself.