What is the sum of the series 1/3 + 2/9 + 3/27 + 4/81 + ........
6416
How can I evaluate $\sum_{n=0}^\infty(n+1)x^n$?
67731
Calculate the sum of infinite series with general term $\frac{n^2}{2^n}$.
70841
A simple series $\sum_{i=1}^\infty \frac{i}{2^i} = 2$
151477
computing the series $\sum_{n=1}^\infty \frac{1}{n^2 2^n}$
123951
Problem calculating sum of convergent series of $\sum_{n=2}^{\infty} \frac{1}{n^{2}-1}$
134633
How to sum this series for $\pi/2$ directly?
142985
Finding sum of series $\sum^{\infty}_{k=0}\frac{(k+1)(k+2)}{2^k}$
43320
Find the sum of the power series $\sum_{n=1}^\infty n*(n+1)*x^n$
100896
What is the sum of this? $ 1 + \frac12 + \frac13 + \frac14 + \frac16 + \frac18 + \frac19 + \frac1{12} +\cdots$
26491
Sum function of a series
113713
Closed formula for the sum of the following series
52241
Calculate sum of series $\sum \frac{n^2}{n!}$
70018
Sum of series (telescoping)
37771
Sum of a power series $n x^n$
155611
Sum of series $\frac{1}{2 \cdot 3 \cdot 4} + \frac{1}{4 \cdot 5 \cdot 6} + \frac{1}{6 \cdot 7 \cdot 8} + \cdots $
102339
How to compute the sum of a series
76387
Evaluate the series $\sum_{n=1}^{\infty} \frac{2^{[\sqrt{n}]}+2^{-[\sqrt{n}]}}{2^n}$