How to calculate the summation of $n \cdot 2^n$?
101908
Solving summations of form $\sum_{i=0}^{\infty} i^kx^i$ without Differentiation and Integration
125148
Summation of series $\sum_{k=0}^\infty 2^k/\binom{2k+1}{k}$
27001
How to calculate the following sum:
33986
Calculate $\sum_{n=1}^{\infty}(\frac{1}{2n}-\frac{1}{n+1}+\frac{1}{2n+4})$
68848
How to simplify $\sum_{k=1}^nk\cdot k!$
78309
On an expansion of $(1+a+a^2+\cdots+a^n)^2$
29524
Formula for the sum $\sum_{i=2}^{n} \frac1{i^2-1}$
116356
Combinatorial proof of $2 \cdot 3^0 + 2 \cdot 3^1 + 2 \cdot 3^2 + \cdots 2 \cdot 3^{n-1} = 3^n-1$
7063
How to compute the  formula $\sum  \limits_{r=1}^d r \cdot 2^r$?
55339
Find the sum $\sum_{n=1}^{\infty}\frac{ 1}{n^{2}(2n-1)}$
44111
Find the value of $\sum_{k=1}^{n}k\binom{n}{k}$?
37059
limit of the sum $\frac{1}{n+1}+\frac{1}{n+2}+\cdots+\frac{1}{2n} $
38741
Finding a general formula for summation
69045
Solving this summation: $\sum_{i=1}^k i\cdot2^i$
80177
Sum from $n=1$ to $N$ of $\sin(nx)/2^n$
123955
How to compute $\sum\limits_{k=0}^n (-1)^k{2n-k\choose k}$?
30724
Summation splitting: $\sum_{n=1}^{\infty} \frac{n}{3\cdot 5\cdot 7 \dots (2n+1)}$