query: Why $\sum_{k=1}^{\infty} \frac{k}{2^k} = 2$?
positive_passages.docid: 6416
positive_passages.text: How can I evaluate $\sum_{n=0}^\infty(n+1)x^n$?
negative_passages.docid: 124229
negative_passages.text: Simplify $\sum_{k=0}^{\infty} x^ky^{\frac{k(k+1)}{2}}$
negative_passages.docid: 56365
negative_passages.text: Evaluate $\sum\limits_{k=1}^{n} \frac{k}{2^k}$
negative_passages.docid: 117056
negative_passages.text: How to show $\sum_{n=1}^{\infty}\frac{H_{n+1}}{n(n+1)}=2$?
negative_passages.docid: 140614
negative_passages.text: Show that $\sum^\infty_{n=m}\frac{1}{n^2} = O(\frac{1}{m})$
negative_passages.docid: 137155
negative_passages.text: Sum $ \sum\limits_{k=1}^{\infty} \frac{k^2}{2^k}$
negative_passages.docid: 137249
negative_passages.text: find $\sum_{k=2}^{\infty}\frac{1}{k^2-1}$
negative_passages.docid: 70841
negative_passages.text: A simple series $\sum_{i=1}^\infty \frac{i}{2^i} = 2$
negative_passages.docid: 55339
negative_passages.text: Find the sum $\sum_{n=1}^{\infty}\frac{ 1}{n^{2}(2n-1)}$
negative_passages.docid: 103572
negative_passages.text: Does $\sum_{m=1}^{\infty}\sum_{n=1}^{\infty}a_{mn}^3=\sum_{n=1}^{\infty}\sum_{m=1}^{\infty}a_{mn}^3$ occur here?
negative_passages.docid: 111524
negative_passages.text: Information on the sum $\sum_{n=1}^\infty \frac{\log n}{n!}$
negative_passages.docid: 92810
negative_passages.text: What is $\sum_{r=1}^\infty\frac{r+2}{2^{r+1}(r)(r+1)}$?
negative_passages.docid: 91784
negative_passages.text: Calculating $\sum_{n=1}^\infty {\frac{1}{2^nn(3n-1)}}$
negative_passages.docid: 117863
negative_passages.text: Series $\sum_{n=1}^\infty \frac{n^n}{(n!)^2}$
negative_passages.docid: 725
negative_passages.text: proof of $\sum_{n=1}^\infty n \cdot x^n= \frac{x}{(x-1)^2}$
negative_passages.docid: 32042
negative_passages.text: Convergence of $\sum_{n=1}^\infty \frac{n^2}{2^n}$
negative_passages.docid: 17056
negative_passages.text: How to find answer to the sum of series $\sum_{n=1}^{\infty}\frac{n}{2^n} $