User Victor - Mathematics Stack Exchange

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	1,244 reputation	bio	website		visits	member for	1 year, 10 months
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89

130

votes

17

answers

8

kviews

Different methods to compute $\sum\limits_{n=1}^\infty \frac{1}{n^2}$

mar 8 at 13:57 xpaul 1

24

86

votes

3

answers

3

kviews

Is 2048 the highest power of 2 with all even digits (base ten)?

number-theory powers

dec 8 at 6:43 Cameron Buie 27.3k

40

63

votes

6

answers

4

kviews

How can you prove that a function has no closed form integral?

calculus real-analysis integration differential-algebra

sep 19 at 17:52 Nils Matthes 1,057

9

40

votes

5

answers

6

kviews

Convergence of $np(n)$ where $p(n)=\sum_{j=\lceil n/2\rceil}^{n-1} {p(j)\over j}$

sequences-and-series probability stochastic-processes

nov 25 '10 at 23:04 Community♦ 1

22

39

votes

1

answer

1

kviews

How to determine with certainty that a function has no elementary antiderivative?

calculus proof-strategy

dec 27 at 20:20 Raymond Manzoni 15.2k

24

34

votes

13

answers

4

kviews

Proving $\int_{0}^{+\infty} e^{-x^2} dx = \frac{\sqrt \pi}{2}$

calculus integral improper-integrals

may 14 at 8:59 Sharkos 4,160

15

34

votes

7

answers

1

kviews

How to explain to the layperson what mathematics is, why it's important, and why it's interesting

soft-question

dec 26 '11 at 23:42 Bruno 6,971

10

31

votes

6

answers

2

kviews

$\sin 1^\circ$ is irrational but how do I prove it in a slick way? And $\tan(1^\circ)$ is …

trigonometry irrational-numbers

mar 22 '12 at 18:46 Community♦ 1

14

29

votes

2

answers

765

views

Prove $\int_0^1 \left| \frac{f^{''}(x)}{f(x)} \right| dx \geq4$

calculus real-analysis

mar 11 '12 at 4:55 Nick Strehlke 3,022

10

24

votes

4

answers

434

views

How to prove that $\int_0^1\left(\sum_{k=n}^\infty {x^k\over k}\right)^2\,dx = \int_0^1 2x^{n-1}\log\left(1+{1\over\sqrt{x}}\right)\,dx.$

integral

may 21 '12 at 5:04 Did 102k

12

23

votes

5

answers

290

views

Closed form for $\prod_{n=1}^\infty\sqrt[2^n]{\frac{\Gamma(2^n+\frac{1}{2})}{\Gamma(2^n)}}$

calculus combinatorics gamma-function closed-form infinite-product

may 13 at 14:14 robjohn♦ 59.2k

12

23

votes

4

answers

2

kviews

Explain $\iint \mathrm dx\mathrm dy = \iint r \mathrm d\alpha\mathrm dr$

calculus integral multivariable-calculus polar-coordinates

nov 30 at 2:36 Michael Hardy 47.9k

15

20

votes

5

answers

814

views

What is so interesting about the zeroes of the $\zeta$ function

number-theory analytic-number-theory riemann-zeta

may 1 at 15:15 anonymous 21

5

19

votes

3

answers

639

views

A problem about floor function

algebra-precalculus

feb 2 '12 at 9:10 Christian Blatter 32.3k

5

17

votes

2

answers

588

views

Largest circle between $y=x^n$ and $y=\sqrt[n]{x}$

geometry functions optimization

may 15 '12 at 21:05 Norbert 19.9k

7

16

votes

1

answer

1

kviews

What do the eigenvectors of an adjacency matrix tell us?

graph-theory eigenvectors spectral-graph-theory

jul 10 at 16:06 tskuzzy 559

1

16

votes

3

answers

262

views

A sum of fractional parts.

combinatorics number-theory problem-solving fractional-part

may 4 '12 at 0:46 Robert Israel 86.1k

6

16

votes

5

answers

979

views

Proof that $\lim_{n\rightarrow \infty} \sqrt[n]{n}=1$

real-analysis

aug 9 '11 at 18:21 Aryabhata 47.5k

7

15

votes

4

answers

386

views

Material in a first course in algebraic geometry?

reference-request algebraic-geometry

mar 1 at 2:39 Victor 1,244

6

14

votes

4

answers

1

kviews

Motivation behind standard deviation?

intuition statistics standard-deviation

sep 17 at 22:00 Michael Hardy 47.9k

4

14

votes

2

answers

526

views

What's the General Expression For Probability of a Failed Gift Exchange Draw

probability combinatorics

dec 3 at 2:21 TestSubject528491 410

6

14

votes

3

answers

2

kviews

The easy(?) part of IMO 2011 Problem 3

functional-equations contest-math

nov 3 '11 at 15:11 Hassan Muhammad 726

1

13

votes

2

answers

846

views

Asking 2011 Putnam B6

elementary-number-theory contest-math problem-solving

dec 4 '11 at 22:15 Asaf Karagila 90.5k

4

13

votes

5

answers

2

kviews

Prime dividing the binomial coefficients

elementary-number-theory prime-numbers binomial-coefficients

feb 18 at 2:20 Bruno 6,971

6

12

votes

4

answers

392

views

How to prove $\sum\limits_{r=0}^n \frac{(-1)^r}{r+1}\binom{n}{r} = \frac1{n+1}$?

algebra-precalculus binomial-coefficients

mar 16 at 2:22 Tea ryur Kwon 1

3

12

votes

1

answer

259

views

Simple but difficult to prove inequality involving integrals

calculus integral

mar 7 '12 at 0:57 Robert Israel 86.1k

3

12

votes

3

answers

293

views

How this integral $ \int_0^z\frac{1-e^x}{x} dx$ is connected to the Gamma function and Euler constant?

complex-analysis integral special-functions

oct 26 '11 at 13:04 Gardel 317

6

12

votes

1

answer

1

kviews

Prove that $\prod_{k=1}^{n-1}\sin\frac{k \pi}{n} = \frac{n}{2^{n-1}}$

trigonometry complex-numbers

nov 1 '10 at 3:47 J. M. 38.9k

7

12

votes

4

answers

584

views

Solving for the implicit function $f\left(f(x)y+\frac{x}{y}\right)=xyf\left(x^2+y^2\right)$ and $f(1)=1$

algebra-precalculus functional-equations contest-math

feb 3 at 1:48 Victor Wang 141

10

12

votes

5

answers

14

kviews

What is Jacobian Matrix?

calculus multivariable-calculus

may 13 at 15:55 Américo Tavares 20.5k

Victor

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