\(lim \sum_{i=0}^{\infty}\frac{N}{2^i}\)
How did you put that sygma symbol?
Cannot type the equations.. So, Here :D
http://www.wolframalpha.com/input/?i=limit+as+n+goes+to+infinity+of+(1%2B(2%2Fn))%5En
Please tell me if you DON'T understand... :)