Finding a closed formula of a given sum
6416
How can I evaluate $\sum_{n=0}^\infty(n+1)x^n$?
32866
How find this sum $\sum\limits_{n=0}^{\infty}\frac{1}{(3n+1)(3n+2)(3n+3)}$
87479
Closed form for $\sum_{k=0}^{n-p}\binom{n}{k}\binom{n}{p+k}$
138072
Linear time algorithm for 2-SUM
42736
Is there a closed form for $\sum_{k=0}^n \frac{x^k}{k!}$?
69439
Infinite Sum of algebraic expression
39199
closed form for $\binom{n}{0}+\binom{n}{3}+\binom{n}{6}+...+\binom{n}{n}$
70041
Sum with parameter convergence
7073
How to get to the formula for the sum of squares of first n numbers?
119606
Closed form of summation
14883
Find $\sum_{n=1}^{\infty}$ $\frac{n^{2}}{\left(n+1\right)\left(n+2\right)\left(n+3\right)\left(n+4\right)}$
103347
combinatorial proof of summation
124135
A general formula for $\sum (k-1)(k-2)(k-3)$?
121617
Closed form of $\sum_{n=0}^{\infty} \frac{\cos(\alpha \, n)}{n!}$
64581
How to find the sum $\sum\limits_{k=1}^n (k^2+k+1)k!$?
43903
Find the sum for $\sum_{n=1}^{\infty}(-1)^{(n+1)}\frac{2n+1}{3^n} $
3798
Finding formula for sum $S_n = \sum_{i=1}^n i(i-1)$