Closed for expression for geometric and arithmetico-geometric series
562
Formula for calculating $\sum_{n=0}^{m}nr^n$
107976
Find a closed formula for $\sum_{n=1}^\infty nx^{n-1}$
58972
Proof/Derivation of Closed form of Binomial Expression $\sum\limits_{k=0}^{2n}(-1)^k\binom{2n}{k}^2$
110262
Finding a closed formula for $1\cdot2\cdot3\cdots k +\dots + n(n+1)(n+2)\cdots(k+n-1)$
145835
Closed form for CRT solution using Euler $\phi\,$ (totient)
26790
Proving the geometric sum formula by induction
10357
Do harmonic numbers have a “closed-form” expression?
69084
What is the closed form for $\sum_{n=1}^\infty \frac1n - \frac1{n+1/p}$?
140462
Find a closed form for the power series $f_p(x)=\sum\limits_{n=0}^\infty\frac{n^p}{n!}x^n$
60877
Geometric series and big theta
10141
Find closed form expression for series expansion coefficients
20945
On a series involving harmonic numbers
51047
Analytic continuation of a power series 2
131080
Geometric representation of the sum of a Geometric Series
128608
Closed form for the series $a+a^p+(a^p)^p+\dots$
133160
Closed form for $\int_0^\infty\frac{1}{(1+x^2)^s}\,dx$ when $s\in (0.5,\infty)\setminus\mathbb{N}$
125933
On the series $\sum \limits_{n=2}^{\infty} \frac{(-1)^n}{n \log n}$