Finite sum $\sum_{j=0}^{n-1} j^2$
7073
How to get to the formula for the sum of squares of first n numbers?
117200
Evaluation of $ \sum_{k=0}^n \cos k\theta $
103840
Calculate $\sum_{k=1}^n k2^{n-k}$
101017
What is the sum of $\sum\limits_{i=1}^{n}ip^i$?
64581
How to find the sum $\sum\limits_{k=1}^n (k^2+k+1)k!$?
123955
How to compute $\sum\limits_{k=0}^n (-1)^k{2n-k\choose k}$?
93837
How to compute infinite series $\sum_{n=0}^{\infty} ne^{-n}$
150822
Finding $\sum_{k=0}^{n-1}\frac{\alpha_k}{2-\alpha_k}$, where $\alpha_k$ are the $n$-th roots of unity
138313
How to sum $\sum_{n=1}^{\infty} \frac{1}{n^2 + a^2}$?
81124
Infinite product problem: $\sum p_n0$
40784
$\sum_{k=m}^{n}(-1)^k\binom{n}{k}\binom{k}{m}=0, n>m\geq 0$
30338
How to prove that $\sum_{k=0}^n \binom nk k^2=2^{n-2}(n^2+n)$
102942
Compute the sum $\sum_{k=1}^{\infty}k^mz^k$ where $|z|<1$
137249
find $\sum_{k=2}^{\infty}\frac{1}{k^2-1}$
54442
Sum of $k {n \choose k}$ is $n2^{n-1}$
127189
sum of this series: $\sum_{n=1}^{\infty}\frac{1}{4n^2-1}$
120215
Sum of elements of a finite field