Spencer, I am skeptical about your formula.

you posted:

$ \sum_{i=1}^n\frac{n}{n - i + 1}\! $

being equal to

$ \sum_{i=1}^n a_i = \frac{n(a_1+a_n)}{2}\! $


Try n=3

original expected value would be 11/2 = 5 1/2

your formula yields 6.

My calculation my be wrong, but otherwise I am thinking I might leave the formula as the answer.


I agree with Ben. $ \sum_{i=1}^n\frac{n}{n - i + 1} = \frac{n}{n} + \frac{n}{n-1} + \dots + \frac{n}{3} + \frac{n}{2} + \frac{n}{1} $ is not an arithmetic series!

-Brian

Alumni Liaison

Prof. Math. Ohio State and Associate Dean
Outstanding Alumnus Purdue Math 2008

Jeff McNeal