robjohn
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175,106
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# 175,106 Reputation

50 today
 +10 14 mins ago upvote What is the sum of the reciprocal of primes? (Yes, it diverges) +10 17 mins ago upvote Parabola is an ellipse, but with one focal point at infinity +10 2 hours ago upvote Why does Benford's Law (or Zipf's Law) hold? +10 6 hours ago upvote What's 4 times more likely than 80%? +10 10 hours ago upvote For a convex function, the average value lies between $f((a+b)/2)$ and $(f(a) + f(b))/2$
230 yesterday
 +105 23:40 11 events $f$ bounded but $f'$ isn't +25 19:46 3 events Binomial theorem and the inequality $(1-e^{-x})^{\alpha}\leq (1-\alpha e^{-x})$ for $0<\alpha\le 1$ +10 20:44 2 events Can anyone suggest a book on Fourier Analysis containing many good problems +10 19:22 7 events Seemingly impossible double integral reduction +10 15:55 upvote Solve the congruence relation $x^n\equiv 2\pmod {13}$. +10 14:51 upvote Is the transformation between these two functions smooth? +10 14:28 upvote Proving that if $a+b$ and $ab$ are of the same parity, then $a$ and $b$ are even. +10 13:46 upvote A question about Lagrange multiplier +10 12:15 upvote Trouble evaluating the sum involving logarithm +10 11:34 upvote How to prove that $\lim\limits_{x\to0}\frac{\sin x}x=1$? +10 03:34 upvote Why does the inversion of the unit circle centered at $-i$ give the horizontal line $y = \frac{1}{2}$? +10 01:03 upvote Limit of a sequence using Hölder's inequality 23:20 4 events How many throws of a die until every possible result is obtained? 21:35 upvote Polygamma function series: $\displaystyle\sum_{k=1}^{\infty }\left(\Psi^{(1)}(k)\right)^2$ 21:06 upvote About the Polya-Knopp-like inequality $\sum_{k=1}^{n}\frac{k^2}{a^2_{1}+\cdots+a^2_{k}}\le\left(\frac{1}{a_{1}}+\cdots+\frac{1}{a_{n}}\right)^2$
155 2 days ago
 +45 21:26 4 events Riemann Zeta Function integral +25 18:48 2 events Probability of getting a certain number: rolling a die with x number of sides, with advantage +15 01:36 accept Cosine double angle formula for complex number angles +10 19:03 upvote Why is the supremum of the empty set $-\infty$ and the infimum $\infty$? +10 16:50 upvote $\int_0^\infty \frac{1}{x^2}\left( \left(\sum_{n=1}^\infty\sin\left(\frac{x}{2^n}\right)\right)-\sin(x)\right)\ dx$ +10 16:06 upvote Does $|n^2 \cos n|$ diverge to $+\infty$? +10 14:43 upvote Limit of a sequence using Hölder's inequality +10 09:51 upvote Computing $\sum{\frac{1}{m^2+n^2}}$ +10 06:36 upvote Show that there is no integer n with $\phi(n)$ = 14 +10 00:13 upvote questions about Rudin's summation by parts
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