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Fedor Petrov's user avatar
Fedor Petrov's user avatar
Fedor Petrov
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question
168
17 camels trick
Jun 7, 2017
answer
69
integral of a "sin-omial" coefficients=binomial
Nov 19, 2016
answer
59
Examples of notably long or difficult proofs that only improve upon existing results by a small amount
Sep 6, 2018
question
54
If any open set is a countable union of balls, does it imply separability?
Sep 18, 2014
answer
54
Most elementary proof showing that exponential growth wins against polynomial growth
Nov 5, 2023
answer
51
The number $\pi$ and summation by $SL(2,\mathbb Z)$
Sep 16, 2016
answer
47
Is every polynomial of the form $2x^{2n} -x^n +1$ irreducible over $\mathbb{Z}$?
Feb 15
answer
43
Prove that expression is integer
Jul 12, 2015
answer
40
Important formulas in combinatorics
Aug 17, 2015
answer
40
Nonequivalent definitions in Mathematics
Nov 22, 2017
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25
Does $8a+5$ ever divide $b^2+8$?
11
Can we partition the plane like this?
9
$ e^{-\mu } \sum_{k=m }^{\infty} \frac{\mu^k}{k!} \le (\frac{\mu}{m})^m e^{m-\mu} $ when $1\le \mu \le m$
7
Prove $ae^{\frac{x}{a}} + be^{-\frac{x}{b}}\leq e^{\frac{x^2}{8a^2b^2}}, \forall x \in \mathbb{R}$ if $a, b > 0; a + b = 1$
6
Trace of symmetric positive semidefinite matrix when diagonalized (as a bilinear form) in a non-orthogonal basis