Finding the closed form of $\sum_{i = 1}^{n - 1}i \cdot 2^{-i}$
562
Formula for calculating $\sum_{n=0}^{m}nr^n$
98941
Closed formula for the sums $\sum\limits_{1 \le i_1 < i_2 < \dots < i_k \le n} i_1 i_2 \cdots i_k $?
146762
Closed form for $\sum_{k=0}^{n} \binom{n}{k}\frac{(-1)^k}{(k+1)^2}$
57780
$\sum_{i=1}^n i\cdot i! = (n+1)!-1$ By Induction
143207
What is $\sum\limits_{i=1}^n \sqrt i\ $?
15164
Proof of $\sum^{2N}_{n=1} \frac{(-1)^{n-1}}{n} = \sum^{N}_{n=1} \frac{1}{N+n}$
125981
Closed-Form Solution to Infinite Sum
110262
Finding a closed formula for $1\cdot2\cdot3\cdots k +\dots + n(n+1)(n+2)\cdots(k+n-1)$
119606
Closed form of summation
125933
On the series $\sum \limits_{n=2}^{\infty} \frac{(-1)^n}{n \log n}$
128608
Closed form for the series $a+a^p+(a^p)^p+\dots$
634
Closed form formula for $\sum\limits_{k=1}^n k^k$
143365
Is $\sum_{i=1}^{n-1}i=\binom{n}{2}$?
94143
Evaluate:: $ 2 \sum_{n=1}^\infty \frac{(-1)^{n+1}}{n+1}\left( 1 + \frac12 +\cdots + \frac 1n\right) $
30895
Compute the sum of the series $\sum_{n=1}^{\infty} \frac{1}{n \cdot 2^n}$
157972
Find a closed form expression for $\sum\limits_{i=0}^{\infty} i^2\cdot x^i$
121617
Closed form of $\sum_{n=0}^{\infty} \frac{\cos(\alpha \, n)}{n!}$