Finding formula for the $n^{th}$ partial sum
26908
Partial Sums of Geometric Series
25232
Is this formula for the $n^{th}$ prime number useful?
110262
Finding a closed formula for $1\cdot2\cdot3\cdots k +\dots + n(n+1)(n+2)\cdots(k+n-1)$
50812
Partial sum of the series $\sum\limits_{r=1}^{\infty} \frac{1}{r(r+1)}$
92754
Closed form for the series: $\sum_{n=1}^{\infty}x^{n^2}$
129801
Finding a closed form for $\sum^{n}_{k=1} \frac{k}{(k+1)!} $
89758
Is there a formula for $(1+i)^n+(1-i)^n$?
7073
How to get to the formula for the sum of squares of first n numbers?
67731
Calculate the sum of infinite series with general term $\frac{n^2}{2^n}$.
634
Closed form formula for $\sum\limits_{k=1}^n k^k$
124135
A general formula for $\sum (k-1)(k-2)(k-3)$?
14884
Compute a sum with partial fraction decomposition and generating functions
64581
How to find the sum $\sum\limits_{k=1}^n (k^2+k+1)k!$?
84213
How to show $n\sum_{i=1}^n {x_i^2} \ge (\sum_{i=1}^n{x_i})^2$
36742
The sum of $(-1)^n \frac{\ln n}{n}$
37771
Sum of a power series $n x^n$
146746
A formula for the sum of the triangular numbers?