need to find sum of $\sum_{k=1}^n \frac{(k-1)2^k}{k(k+1)}$
38741
Finding a general formula for summation
127806
How to find the sum of the series $\sum_{k=2}^\infty \frac{1}{k^2-1}$?
113189
Find the sum of the series $1^2-2^2+3^2-4^2+...-(2n)^2$
5272
Proving that $\sum_{k=0}^{n}\frac{(-1)^k}{{n\choose k}}=[1+(-1)^n] \frac{n+1}{n+2}.$
106028
Sum of $\frac{1}{(2n)(2n+1)}$ from $1$ to infinity
47706
Find the value of $ \sum_{n=1}^{\infty} \frac{n^3}{3^n} $
14223
Find the infinite sum $\sum_{n=1}^{\infty}\frac{1}{2^n-1}$
57503
How find $\sum_{k \in A} \frac{1}{k-1} $ for $ A = \{ m^n| \text{ } m, n \in Z \text { and } m, n \ge 2 \} $
84147
Evaluating $\sum_{n=1}^\infty \frac{2^{2n-1}}{5^{n+1}}$
64581
How to find the sum $\sum\limits_{k=1}^n (k^2+k+1)k!$?
138542
Evaluating sums question $\sum_{k=2}^n \frac{1}{k^2-1}$
20271
Proving $\sum_{k=1}^n{k^2}=\frac{n(n+1)(2n+1)}{6}$ without induction
153226
Proof of $\sum_{k = 1}^{n} \frac{1}{k^{2}} < 2 - \frac{1}{n}$
14883
Find $\sum_{n=1}^{\infty}$ $\frac{n^{2}}{\left(n+1\right)\left(n+2\right)\left(n+3\right)\left(n+4\right)}$
9610
Find the sum of $\sum\limits_{n=1}^{\infty} \frac{x^{n}}{n(n+1)}$
57549
Finding the sum $\sum_{k=1}^rk^2\binom {n-k}{r-k}$
133955
Compute: $\sum_{k=1}^{\infty}\sum_{n=1}^{\infty} \frac{1}{k^2n+2nk+n^2k}$