User Thomas Browning

11 votes

How to compute $\sum_{k=1}^{\infty}{\frac{1}{k^2+2k}}$?

answered Jun 16, 2019 at 0:24

10 votes

Accepted

Let G be a group of order $pqr$,where $p<q<r$ are primes. Prove that the Sylow r-group is normal.

answered Jul 20, 2019 at 16:35

8 votes

$3^n$ does not divide $4^n+5$ for $n\geq 2$

answered Apr 21, 2020 at 19:06

7 votes

Accepted

Is $S$ is open in $\mathbb{R}^2$?

answered Jul 2, 2019 at 19:45

7 votes

If $I\cong G/H$, where $I$ is a subgroup of $G$, why is $G=IH$?

answered Dec 9, 2019 at 23:23

7 votes

The Heegner Polynomials

answered Feb 17, 2022 at 23:08

7 votes

Accepted

Show that $3^{7^n}+5^{7^n}\equiv 1 \pmod{7^{n+1}}$

answered Jul 2, 2019 at 19:40

6 votes

Accepted

Parametrization of the curve $x^{x^y}=y$

answered Sep 26, 2020 at 7:01

6 votes

Accepted

Is $S_6$ the derived subgroup of some group?

answered Dec 15, 2019 at 16:38

4 votes

Accepted

Normalizer of a solvable maximal subgroup

answered Nov 21, 2019 at 22:32

4 votes

Eulerian graph has three vertices of the same degree

answered Jun 7, 2018 at 7:03

3 votes

Binomial identity in a Change of Basis Matrix

answered Oct 15, 2016 at 21:25

3 votes

Proving the following inequality without using AM-GM inequality.

answered Jun 7, 2018 at 6:45

3 votes

Accepted

Which group of order 24 is this group?

answered Jun 27, 2018 at 21:37

3 votes

Accepted

Show that a finite abelian group is cyclic if and only if every Sylow-p-subgroups are cyclic.

answered Jul 6, 2019 at 20:48

3 votes

Classify the groups of order $88$ up to isomorphism.

answered Mar 21, 2020 at 20:00

2 votes

If $H \unlhd G$ then is $H \unlhd G \rtimes K$

answered Oct 17, 2021 at 23:37

2 votes

Accepted

Is the image of a cyclic group $G$ a normal subgroup?

answered Dec 7, 2019 at 5:04

2 votes

Accepted

How big must the union of a group's Sylow p-subgroups be?

answered Jan 8, 2021 at 5:04

2 votes

If $2^{2k}-x^2\bigm|2^{2k}-1$ then $x=1$

answered Nov 21, 2020 at 10:23

2 votes

Let $H$, $K$ be subgroup of $G$. Does $|HK|$ always divide $|G|$?

answered Oct 17, 2018 at 15:25

1 vote

Construct coordinates of $n+1$ points in ${\mathbb{R}^n}$, each pair of which have the same distance

answered Nov 12, 2018 at 5:23

1 vote

Prove $s_1 = 4, s_{n+1} = \sqrt{3s_n -2}$ Convergent Sequence

answered Jul 25, 2016 at 6:18

1 vote

Classify all groups of order $p^2q^2$ up to isomorphism

answered Aug 20, 2019 at 0:02

1 vote

Accepted

Find the order of permutation groups

answered Jul 2, 2019 at 17:08

1 vote

Accepted

A few questions on $\mathrm{Aut}(G)$ when $G$ is finite

answered Jul 2, 2019 at 2:55

1 vote

An inequality with a prime number

answered Aug 22, 2018 at 7:23

1 vote

Proving the Deduction Theorem

answered Sep 7, 2018 at 5:56

1 vote

Accepted

An infinite family of generalized Pell equations

answered Dec 21, 2020 at 23:20

1 vote

Accepted

Group Law on Specific Elliptic Curve

answered Jul 25, 2021 at 3:05

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39 Answers

How to compute $\sum_{k=1}^{\infty}{\frac{1}{k^2+2k}}$?

Let G be a group of order $pqr$,where $p<q<r$ are primes. Prove that the Sylow r-group is normal.

$3^n$ does not divide $4^n+5$ for $n\geq 2$

Is $S$ is open in $\mathbb{R}^2$?

If $I\cong G/H$, where $I$ is a subgroup of $G$, why is $G=IH$?

The Heegner Polynomials

Show that $3^{7^n}+5^{7^n}\equiv 1 \pmod{7^{n+1}}$

Parametrization of the curve $x^{x^y}=y$

Is $S_6$ the derived subgroup of some group?

Normalizer of a solvable maximal subgroup

Eulerian graph has three vertices of the same degree

Binomial identity in a Change of Basis Matrix

Proving the following inequality without using AM-GM inequality.

Which group of order 24 is this group?

Show that a finite abelian group is cyclic if and only if every Sylow-p-subgroups are cyclic.

Classify the groups of order $88$ up to isomorphism.

If $H \unlhd G$ then is $H \unlhd G \rtimes K$

Is the image of a cyclic group $G$ a normal subgroup?

How big must the union of a group's Sylow p-subgroups be?

If $2^{2k}-x^2\bigm|2^{2k}-1$ then $x=1$

Let $H$, $K$ be subgroup of $G$. Does $|HK|$ always divide $|G|$?

Construct coordinates of $n+1$ points in ${\mathbb{R}^n}$, each pair of which have the same distance

Prove $s_1 = 4, s_{n+1} = \sqrt{3s_n -2}$ Convergent Sequence

Classify all groups of order $p^2q^2$ up to isomorphism

Find the order of permutation groups

A few questions on $\mathrm{Aut}(G)$ when $G$ is finite

An inequality with a prime number

Proving the Deduction Theorem

An infinite family of generalized Pell equations

Group Law on Specific Elliptic Curve