Evaluate a sum which almost looks telescoping but not quite:$\sum_{k=2}^n \frac{1}{k(k+2)}$
111602
Help with telescoping sum $\sum_{i=3}^n \frac{1}{i(i+3)} $
49851
when the sum of some fractions be $1$
51008
Evaluating a sum involving binomial coefficient in denominator
17638
Sum with binomial coefficients: $\sum_{k=0}^{n}{2n\choose 2k}$
4573
Explicitly finding the sum of $\arctan(1/(n^2+n+1))$
104646
Question on simplification of $\sum_{n=1}^{\infty}\frac{2}{(2n+1)(2n+3)}$?
52278
How to solve $\sum_{k=2}^\infty {\frac{1}{k^2-1}}$
117200
Evaluation of $ \sum_{k=0}^n \cos k\theta $
70841
A simple series $\sum_{i=1}^\infty \frac{i}{2^i} = 2$
134610
Find the sum of finite series $S=\sum_{k=1}^{2015}{(-1)^{\frac{k(k+1)}{2}}}k$
127267
Evaluation of $\sum_{n=1}^{\infty}\frac{1}{n(2n+1)}=2-2\ln(2)$
17686
Evaluate the infinite series $\sum_{r=1}^{\infty} \frac{2^{-r}}{r^{2}}$
326
Find $\sum_{k=1}^{\infty}\frac{1}{2^{k+1}-1}$
28489
Estimating partial sums $\sum_{n = 1}^m \frac{1}{\sqrt{n}}$
130083
Evaluating sum of a combination series
117056
How to show $\sum_{n=1}^{\infty}\frac{H_{n+1}}{n(n+1)}=2$?
56365
Evaluate $\sum\limits_{k=1}^{n} \frac{k}{2^k}$