The sum of $(x-1) + (x-2) + ... + 1$ series
2675
Proof $1+2+3+4+\cdots+n = \frac{n\times(n+1)}2$
134361
Calculating the sum of a binomial coefficient series
99420
Compute $\sum_{n=1}^\infty \frac{1}{(n+1)\sqrt[]{n}+n\sqrt[]{n+1}}$
37771
Sum of a power series $n x^n$
81589
Find the sum of $\sum_{k=0}^{\infty} 1/[(r+2k+2)(s+2k+2)]$
151085
Simplify the sum $ \sum_{i=0}^{k}(-1)^i i \binom{n}{i} \binom{n}{k-i}$
117863
Series $\sum_{n=1}^\infty \frac{n^n}{(n!)^2}$
70841
A simple series $\sum_{i=1}^\infty \frac{i}{2^i} = 2$
130083
Evaluating sum of a combination series
150148
Sum of $\sum^\infty_{n=2} \frac{1}{\ln{(n!)}}$
28378
Find the infinite sum of the series $\sum_{n=1}^\infty \frac{1}{n^2 +1}$
74117
Find the sum of series $\sum_{n=0}^{\infty}\frac{z^{kn}}{(kn)!}$
120633
How to find sum of this series $\sum_{0}^{\infty} \frac{(n!)^{2}x^{n}}{(2n)!}$
83641
The sum of the series $\frac{15}{16}+\frac{15}{16} \times \frac{21}{24}+\frac{15}{16} \times \frac{21}{24} \times \frac{27}{32}+\dots$
120988
Infinite Series $\sum 1/(n(n+1))$
29524
Formula for the sum $\sum_{i=2}^{n} \frac1{i^2-1}$
35036
Series $\sum_{n=1}^{\infty}\frac{\cos(nx)}{n^2}$