User ccorn - Mathematics Stack Exchange

33 votes

Accepted

How prove this $\sum_{k=1}^{2^{n-1}}\sigma{(2^n-2k+1)}\sigma{(2k-1)}=8^{n-1}$

answered Jul 17, 2013 at 23:02

30 votes

Galois group of $x^4-5$

answered Jan 6, 2014 at 23:49

22 votes

Accepted

Coefficient of $n$th cyclotomic polynomial equals $-\mu(n)$

answered Apr 3, 2014 at 10:17

22 votes

Is there a good way to compute Christoffel Symbols

answered Apr 10, 2016 at 22:51

15 votes

I found this odd relationship, $x^2 = \sum_\limits{k = 0}^{x-1} (2k + 1)$.

answered Mar 3, 2014 at 14:06

15 votes

Binomial Identity $\sum\binom{2n+1}{2k+1}\binom{m+k}{2n} = \binom{2m}{2n}$

answered Dec 11, 2013 at 12:17

15 votes

Accepted

Generalizing the sum of consecutive cubes $\sum_{k=1}^n k^3 = \Big(\sum_{k=1}^n k\Big)^2$ to other odd powers

answered Nov 6, 2013 at 21:48

15 votes

Common Math Mistakes Made by Scientists

answered Nov 22, 2013 at 2:16

14 votes

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Ramanujan's tau function identity

answered Jul 16, 2015 at 23:00

14 votes

What is the norm function in $\mathcal{O}_{\mathbb{Q}(\zeta_8)}$?

answered Sep 24, 2018 at 21:55

13 votes

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How to prove that trace$(ABA^{-1}B^{-1})$=$3$

answered Dec 20, 2016 at 5:33

13 votes

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How to prove that $\frac{\eta^{14}(q^4)}{\eta^{4}(q^8)}=4\eta^4(q^2)\eta^2(q^4)\eta^4(q^8)+\eta^4(q)\eta^2(q^2)\eta^4(q^4)$?

answered Sep 7, 2013 at 22:15

12 votes

Why 1728 in $j$-invariant?

answered Oct 19, 2013 at 15:21

12 votes

Graphically locate the axes or foci of an ellipse from 5 arbitrary points on its perimeter.

answered Mar 1, 2022 at 15:11

10 votes

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Show that $f = x^5 + 5x^3 + 1 \in \mathbb Q[x]$ is irreducible

answered Jul 28, 2013 at 21:37

10 votes

Accepted

Good description of orbits of upper half plane under $SL_2 (Z)$

answered Nov 28, 2015 at 7:19

10 votes

Polynomial roots problems.

answered May 27, 2016 at 20:16

9 votes

Foci of a general conic equation

answered Jan 19, 2017 at 0:22

9 votes

About the roots of cubic polynomial

answered Jan 25, 2017 at 22:09

8 votes

Accepted

Finding a quartic polynomial in $\mathbb{Q}[X]$ with four real roots such that Galois group is ${S_4}$.

answered Jun 26, 2015 at 23:07

8 votes

Accepted

Polynomial factorisation - absolute value of coefficients

answered Oct 31, 2014 at 16:15

8 votes

Is there a precise mathematical connection between hypergeometric functions and modular forms

answered Feb 9, 2014 at 16:34

8 votes

Accepted

$q$-series identity

answered Mar 13, 2014 at 14:42

8 votes

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parallel curvature imply constant Ricci and scalar curvature

answered May 11, 2014 at 14:37

7 votes

Accepted

Finding the Norm of an element in a field extension

answered May 5, 2014 at 19:59

7 votes

Accepted

Where does Klein's j-invariant take the values 0 and 1, and with what multiplicities?

answered Dec 2, 2013 at 13:49

7 votes

Best algebraic approximations

answered Jul 3, 2017 at 14:43

6 votes

Accepted

On the cubic generalization $(a^3+b^3+c^3+d^3)(e^3+f^3+g^3+h^3 ) = v_1^3+v_2^3+v_3^3+v_4^3$ for the Euler four-square

answered Feb 17, 2018 at 14:10

6 votes

Accepted

Chazy equation and movable singularity

answered May 24, 2017 at 9:51

6 votes

How to compute 2-adic square roots?

answered May 28, 2017 at 9:02

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209 Answers

How prove this $\sum_{k=1}^{2^{n-1}}\sigma{(2^n-2k+1)}\sigma{(2k-1)}=8^{n-1}$

Galois group of $x^4-5$

Coefficient of $n$th cyclotomic polynomial equals $-\mu(n)$

Is there a good way to compute Christoffel Symbols

I found this odd relationship, $x^2 = \sum_\limits{k = 0}^{x-1} (2k + 1)$.

Binomial Identity $\sum\binom{2n+1}{2k+1}\binom{m+k}{2n} = \binom{2m}{2n}$

Generalizing the sum of consecutive cubes $\sum_{k=1}^n k^3 = \Big(\sum_{k=1}^n k\Big)^2$ to other odd powers

Common Math Mistakes Made by Scientists

Ramanujan's tau function identity

What is the norm function in $\mathcal{O}_{\mathbb{Q}(\zeta_8)}$?

How to prove that trace$(ABA^{-1}B^{-1})$=$3$

How to prove that $\frac{\eta^{14}(q^4)}{\eta^{4}(q^8)}=4\eta^4(q^2)\eta^2(q^4)\eta^4(q^8)+\eta^4(q)\eta^2(q^2)\eta^4(q^4)$?

Why 1728 in $j$-invariant?

Graphically locate the axes or foci of an ellipse from 5 arbitrary points on its perimeter.

Show that $f = x^5 + 5x^3 + 1 \in \mathbb Q[x]$ is irreducible

Good description of orbits of upper half plane under $SL_2 (Z)$

Polynomial roots problems.

Foci of a general conic equation

About the roots of cubic polynomial

Finding a quartic polynomial in $\mathbb{Q}[X]$ with four real roots such that Galois group is ${S_4}$.

Polynomial factorisation - absolute value of coefficients

Is there a precise mathematical connection between hypergeometric functions and modular forms

$q$-series identity

parallel curvature imply constant Ricci and scalar curvature

Finding the Norm of an element in a field extension

Where does Klein's j-invariant take the values 0 and 1, and with what multiplicities?

Best algebraic approximations

On the cubic generalization $(a^3+b^3+c^3+d^3)(e^3+f^3+g^3+h^3 ) = v_1^3+v_2^3+v_3^3+v_4^3$ for the Euler four-square

Chazy equation and movable singularity

How to compute 2-adic square roots?