Trick to solving this Summation?
69045
Solving this summation: $\sum_{i=1}^k i\cdot2^i$
41251
making a big summation sign
45588
Summing a series with a changing power
15932
How to simplify the summation kk! without using induction?
103347
combinatorial proof of summation
17056
How to find answer to the sum of series $\sum_{n=1}^{\infty}\frac{n}{2^n} $
103840
Calculate $\sum_{k=1}^n k2^{n-k}$
75457
How do i simplify the following: $\sum_{i=1}^n (3i^2+4) - \sum_{j=2}^{n+1} (3j^2+1)$
113189
Find the sum of the series $1^2-2^2+3^2-4^2+...-(2n)^2$
71824
Finding the sum of the series $\frac{1}{1!}+\frac{1+2}{2!}+\frac{1+2+3}{3!}+ \ldots$
27001
How to calculate the following sum:
121554
Finding $\sum\frac{1}{2^n(n+1)}$
118387
How to extend summations to fractional orders?
115433
Find the summation of given expression: $\sum_{k=1}^n k^3\binom nk$
143945
Summation of combination of binomial coefficient
3798
Finding formula for sum $S_n = \sum_{i=1}^n i(i-1)$
8806
Summation of binomial coefficients