How to calculate $\sum_{k=1}^n k*2^{n-k}$
103840
Calculate $\sum_{k=1}^n k2^{n-k}$
78632
Summation equation for $2^{x-1}$
91784
Calculating $\sum_{n=1}^\infty {\frac{1}{2^nn(3n-1)}}$
11612
How to show that $\sum_{k=1}^n k(n+1-k)=\binom{n+2}3$?
88973
How do you calculate this sum $\sum_{n=1}^\infty nx^n$?
121554
Finding $\sum\frac{1}{2^n(n+1)}$
89136
How prove this $\sum_{k=1}^{2^{n-1}}\sigma{(2^n-2k+1)}\sigma{(2k-1)}=8^{n-1}$
151179
Finding the value of $\sum k/3^k$
33986
Calculate $\sum_{n=1}^{\infty}(\frac{1}{2n}-\frac{1}{n+1}+\frac{1}{2n+4})$
5332
Find the value of $\sum_0^n \binom{n}{k} (-1)^k \frac{1}{k+1}$
135927
Calculating $\sum_{n=1}^\infty\frac{1}{(n-1)!(n+1)}$
3798
Finding formula for sum $S_n = \sum_{i=1}^n i(i-1)$
562
Formula for calculating $\sum_{n=0}^{m}nr^n$
99453
Sum of $k$-th powers
36361
How to calculate the summation $(\sum_{p = k}^{n} \binom{n}{p}) / 2^n$ quickly?
37771
Sum of a power series $n x^n$
136580
Proving $\sum_{k=0}^n\binom{2n}{2k} = 2^{2n-1}$