334 How can I evaluate $\sum_{n=0}^\infty(n+1)x^n$? 146 $\int_{-\infty}^{+\infty} e^{-x^2} dx$ with complex analysis 124 Direct Proof that $1 + 3 + 5 + \cdots+ (2n - 1) = n\cdot n$ 96 100 Soldiers riddle 87 What is special about the numbers 9801, 998001, 99980001 ..?

Reputation (61,207)

 +10 How do I get the square root of a complex number? +10 Order of product of two elements in a group +10 How can I evaluate $\sum_{n=0}^\infty(n+1)x^n$? +10 A problem about the largest prime factor of $n^2+1$

Questions (31)

 261 The Mathematics of Tetris 62 Limits: How to evaluate $\lim\limits_{x\rightarrow \infty}\sqrt[n]{x^{n}+a_{n-1}x^{n-1}+\cdots+a_{0}}-x$ 36 Fermat's Last Theorem and Kummer's Objection 34 A series problem by Knuth 31 Explicitly reconstructing a function from its moments

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 1k sequences-and-series × 107 589 elementary-number-theory × 62 1k number-theory × 159 585 integration × 62 876 analytic-number-theory × 144 455 convergence × 25 728 calculus × 102 447 complex-analysis × 51 614 prime-numbers × 77 376 faq × 7