Is there a closed formula for the sum $q+q^2+q^4+\dots+q^{2^n}$?
110996
Sum of the form $r+r^2+r^4+\dots+r^{2^k} = \sum_{i=1}^k r^{2^i}$
81589
Find the sum of $\sum_{k=0}^{\infty} 1/[(r+2k+2)(s+2k+2)]$
63965
How can I compute the sum of $ {m\over\gcd(m,n)}$?
20550
Generalized Euler sum $\sum_{n=1}^\infty \frac{H_n}{n^q}$
124135
A general formula for $\sum (k-1)(k-2)(k-3)$?
153465
Is there a closed form expression for $1 + x + x^{4} + x^{9}+x^{16}+x^{25} +..+x^{k^2}$?
42736
Is there a closed form for $\sum_{k=0}^n \frac{x^k}{k!}$?
136066
Find the sum $\sum _{n=1}^{\infty }\left(\sqrt{n+2}-2\sqrt{n+1}+\sqrt{n}\right)$
23726
A closed form for $1^{2}-2^{2}+3^{2}-4^{2}+ \cdots + (-1)^{n-1}n^{2}$
143428
How to sum $\sum_{x=0}^{N-1} \cos{\left( \frac{2\pi x}{N} \right)}^{2}$?
121029
How do I add summation formula's like this: $F(n+2) = 1 + \sum\limits_{i=0}^{n} F(i)$?
59253
Summing the power series $\sum\limits_{n=0}^\infty (-1)^n \frac{x^{2n+1}}{2n+1}\prod\limits_{k=1}^n\frac{2k-1}{2k} $
39199
closed form for $\binom{n}{0}+\binom{n}{3}+\binom{n}{6}+...+\binom{n}{n}$
142882
Can the factorial function be written as a sum?
152698
Evaluation of $\sum_{n=0}^{\infty}\frac{1}{(n^4+n^2+1)n!}$
68725
Find expression for : $ S_n =\sum_{i=1}^{n} \frac{i}{i^4+i^2+1} $
83641
The sum of the series $\frac{15}{16}+\frac{15}{16} \times \frac{21}{24}+\frac{15}{16} \times \frac{21}{24} \times \frac{27}{32}+\dots$