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25 votes

The $2\pi$ in the definition of the Fourier transform

answered Mar 23, 2017 at 14:27

23 votes

Accepted

A finite alternating sum

answered Oct 27, 2019 at 23:59

20 votes

Accepted

Inverse of special upper triangular matrix

answered Aug 29, 2017 at 13:22

19 votes

Accepted

Harmonic sums and elementary number theory

answered Dec 1, 2019 at 18:06

14 votes

Generalizing a problem to make it easier

answered Jul 5, 2020 at 23:02

13 votes

Is it true that $\sum_{k=m}^n\frac{\sigma(k)}k\not\in\mathbb Z$ for all derangements $\sigma\in S_n$ and $1\le m\le n$?

answered Nov 27, 2018 at 14:13

9 votes

Accepted

Partition of [3n] into summoids

answered Aug 11, 2017 at 3:03

9 votes

If $x_{n+1}= \frac{nx_{n}^2+1}{n+1}$ then $x_{n}=1$

answered Aug 13, 2017 at 14:38

9 votes

Accepted

There at least 4 divisors of $n-1$ which do not divide $\phi(n)$ if $n$ is a composite of the form $6k+1$

answered Jul 29, 2016 at 13:51

8 votes

Accepted

Tensor product of field extensions

answered Sep 1, 2017 at 2:32

6 votes

Any interesting properties of the matrix $M:=(m_{ij})$ with $m_{ij}=\min(i,j)$?

answered Aug 3, 2015 at 10:15

6 votes

Fixed point for a map from $\{0,1\}^N$ to itself

answered Oct 8, 2020 at 16:24

6 votes

Solution to simple mathematical game

answered Sep 30, 2019 at 18:42

5 votes

How can you find a divisor of the numerator of 1-1/2+1/3-1/4-...+1/47

answered Jul 18, 2018 at 12:34

5 votes

Elementary results with p-adic numbers

answered Jul 19, 2019 at 18:50

4 votes

Examples of "unsuccessful" theories with afterlives

answered Sep 20, 2019 at 20:18

4 votes

Accepted

Summation involving Euler's totient function

answered Sep 27, 2019 at 17:12

4 votes

What structure do you get if you adjoint a root of $z \bar{z} = -1$ to the complex numbers?

answered Dec 15, 2016 at 14:31

4 votes

Is it possible to describe the image of the $p$-adic logarithm on $1+\mathfrak{m}$, where $\mathfrak{m}$ is the maximal ideal of a $p$-adic field?

answered Aug 10, 2017 at 8:39

4 votes

Accepted

Primes from arithmetic and geometric progressions

answered Oct 2, 2019 at 14:47

4 votes

How to prove $(\phi-1)(\phi-2)...(\phi-p) = \sqrt{5} + p\left(\frac{1}{2}+A\sqrt{5}\right) \bmod p^2$?

answered Oct 27, 2019 at 3:08

3 votes

Does $n^2$ divide $\det\left[\left(\frac{i^2+2ij+3j^2}n\right)\right]_{1\le i,j\le n-1}$ for each odd integer $n>3$?

answered Jun 12, 2018 at 17:22

2 votes

Accepted

Upper Bound on minimum number of lattice points

answered Aug 26, 2017 at 12:52

2 votes

Accepted

Seeking for a meaning: a curious symmetry

answered Jun 19, 2017 at 15:45

2 votes

Accepted

Inverse image of norm map on principal units for an unramified extension

answered Jul 6, 2017 at 9:59

2 votes

Compute the kernel of multiplication of algebraic numbers

answered Jul 31, 2016 at 15:16

2 votes

Accepted

Projective modules and gradings

answered Nov 17, 2019 at 23:43

2 votes

Results on additive structure of polynomial rings?

answered Nov 21, 2019 at 20:53

1 vote

another generalized Lehmer-Euler-conjecture

answered Aug 12, 2016 at 9:24

1 vote

Some references for f-ring

answered Jul 23, 2015 at 1:28

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32 Answers

The $2\pi$ in the definition of the Fourier transform

A finite alternating sum

Inverse of special upper triangular matrix

Harmonic sums and elementary number theory

Generalizing a problem to make it easier

Is it true that $\sum_{k=m}^n\frac{\sigma(k)}k\not\in\mathbb Z$ for all derangements $\sigma\in S_n$ and $1\le m\le n$?

Partition of [3n] into summoids

If $x_{n+1}= \frac{nx_{n}^2+1}{n+1}$ then $x_{n}=1$

There at least 4 divisors of $n-1$ which do not divide $\phi(n)$ if $n$ is a composite of the form $6k+1$

Tensor product of field extensions

Any interesting properties of the matrix $M:=(m_{ij})$ with $m_{ij}=\min(i,j)$?

Fixed point for a map from $\{0,1\}^N$ to itself

Solution to simple mathematical game

How can you find a divisor of the numerator of 1-1/2+1/3-1/4-...+1/47

Elementary results with p-adic numbers

Examples of "unsuccessful" theories with afterlives

Summation involving Euler's totient function

What structure do you get if you adjoint a root of $z \bar{z} = -1$ to the complex numbers?

Is it possible to describe the image of the $p$-adic logarithm on $1+\mathfrak{m}$, where $\mathfrak{m}$ is the maximal ideal of a $p$-adic field?

Primes from arithmetic and geometric progressions

How to prove $(\phi-1)(\phi-2)...(\phi-p) = \sqrt{5} + p\left(\frac{1}{2}+A\sqrt{5}\right) \bmod p^2$?

Does $n^2$ divide $\det\left[\left(\frac{i^2+2ij+3j^2}n\right)\right]_{1\le i,j\le n-1}$ for each odd integer $n>3$?

Upper Bound on minimum number of lattice points

Seeking for a meaning: a curious symmetry

Inverse image of norm map on principal units for an unramified extension

Compute the kernel of multiplication of algebraic numbers

Projective modules and gradings

Results on additive structure of polynomial rings?

another generalized Lehmer-Euler-conjecture

Some references for f-ring