**4**

votes

**2**answers

200 views

### Explicit $2$-descent on elliptic curves

Let $k$ be a field of characteristic $0$ and let
$$E: y^2 = f(x)$$
be an elliptic curve over $k$, with $\mathrm{deg}(f) = 3$. Kummer theory yields a map
$$\varphi:\mathrm{H}^1(k, E[2]) \to ...

**4**

votes

**1**answer

172 views

### Estimates of a sum involving both the Möbius function and Mertens function

I want to ask on the estimates of the sum
$$ \sum_{n=1}^{\infty} \mu(n)M\Big(\frac{x}{n}\Big)=\frac{1}{2\pi i }\int_{\gamma-i\infty}^{\gamma+i\infty}\frac{x^s}{s\zeta(s)^2}ds.$$
It seems that the ...

**15**

votes

**2**answers

547 views

### A conjecture about $\lfloor n!\cdot q/e\rfloor-\,!n\cdot q$

I was thinking about this question asked at Math.SE, when I came up with the following conjecture.
For every $q\in\mathbb Q$ consider a sequence $s_n^{(q)}$ (terms within the sequence are indexed by ...

**3**

votes

**1**answer

271 views

### Unramified extension of number fields

Any finite field extension (in particular Galois extension) of $\mathbb{Q}$ is ramified. Is there an intuitive geometric explanation of this fact?
Suppose we have an number field $K$, is any Galois ...

**2**

votes

**3**answers

358 views

### Hard inequality and number theory [closed]

Let $m,n \in \mathbb{N}$ and $m \geq n \geq 2$ and $x_1,x_2,...x_n \in \mathbb{N}_{\geq 1}$ such as $x_1+x_2+...+x_n=m$.
Find $\min P$ with $P= \sum_{i=1}^{n} x_i^2.$

**17**

votes

**1**answer

387 views

### For a linear recurrence sequence $(u_n)_{n\geq 0}$, can $\{i \mid u_i > 0\}$ be the set of Fibonacci numbers?

Question: Is there a linear recurrence sequence $(u_n)_{n\geq0}$ (on the rationals, but I would also be interested by reals) for which $\text{Pos}(u) = \{i \mid u_i > 0\}$ is precisely the set of ...

**0**

votes

**0**answers

55 views

### uniqueness of $p$-regular infinite continued fraction expansion

I'm not sure what's the accepted terminology is in this regard, but --- following M. Kojima --- let us call a $p$-regular infinite continued
fraction $\big[a_0, a_1, a_2, \dots \big]$ an expansion of ...

**11**

votes

**0**answers

169 views

### Are Hecke eigenvalues on the cohomology of the Newton polygon strata automorphic?

Fix a genus $g$, a prime $p$, and a Newton polygon $\Delta$ of an abelian variety of genus $g$.
Let $\mathcal A_{g, \overline{\mathbb F}_p, \Delta}$ be the moduli stack of abelian varieties of genus ...

**5**

votes

**0**answers

283 views

### A problem on prime numbers

Given integers $a,b,c,d\in[2^n,2^m]$ with $m>n>1$, how many primes $p$ are there in $[n^\alpha,n^\beta]$ for some $1<\alpha<\beta$ such that
$$0<a\bmod p<n^{\alpha/k}$$
$$0<b\bmod ...

**8**

votes

**1**answer

244 views

### Primes in arithmetic progression with a moduli equal to a power of 2

I am currently looking for a result stronger than Siegel-Walfisz theorem, which gives an upper bound on the error term $|\pi(x,a,b)-\frac{\pi(x)}{\phi(a)}|$ for particular $a$.
The Siegel Walfisz is ...

**6**

votes

**1**answer

207 views

### Integral points on elliptic curves of the form $y^2=x^3+px$

As the title says. Can we determine all the integral points on elliptic curves of the form
$$y^2=x^3+px$$
for a prime $p$? If yes, can someone explain me how? A good reference would also be ...

**4**

votes

**1**answer

167 views

### What is known about the largest prime divisor of the product of $k$ consecutive integers?

Take $k$ consecutive composite integers from a prime gap. What is known about the largest prime divisor of their product?
It seems to me that except for the triplet $(8,9,10)$ and the pair $(8,9)$ , ...

**11**

votes

**1**answer

404 views

### Two Vinogradovs? Is one the son of the other? [closed]

Forgive me for my ignorance, but I'm very surprised to learn that there are two Vinogradovs, both famous in the field of analytic number theory. Guessing from their names and the Russian naming ...

**0**

votes

**0**answers

154 views

### Name of some commutative ring akin to $p$-adics

I need help in identifying the naming convention of some commutative ring described below.
Let $p$ be a prime, let $k$ be a positive integer, and let $$\textbf{e} = (e_0,\ldots,e_{k-1})$$ be a list ...

**2**

votes

**1**answer

192 views

### Conductor of a CM elliptic curve and its Grössencharacter

For a CM elliptic curve $E$ and its Grössencharakter, their conductors are both supported on bad primes of $E$. Moreover, by comparing their functional equation, there should be some obvious ...

**4**

votes

**1**answer

266 views

### Upper bound for the first Hardy-Littlewood conjecture

About the Hardy-Littlewood conjecture by Terence Tao:
Conjecture 2 (Prime tuples conjecture, quantitative form) Let ${k_0 \geq 1}$ be a fixed natural number, and let ${{\mathcal H}}$ be a fixed ...

**4**

votes

**2**answers

123 views

### Explicit constant terms of volumes of moduli spaces

In Simple geodesics and Weil-Petersson volumes of moduli spaces of bordered Riemann surfaces, Mirzakhani gave a recursive formula for WP volumes of moduli spaces $\mathcal{M}_{g,n}(L)$ of bordered ...

**2**

votes

**0**answers

286 views

### How big can a set of integers be if all pairs have bounded gcd

In this recent MO question, it was shown that the maximal cardinality of a subset $A(M,N)$ of $[1,N]$ where the pairwise GCD's of all set elements are upper bounded by $M,$ with $M^2\leq N$ has size ...

**11**

votes

**1**answer

379 views

### Why does genus control the number of points

Often number theorists can bound the number of solutions to a diophantine equation based on the size of the points and the size of the coefficients. But this, as I understand it, can be a bit of a red ...

**4**

votes

**0**answers

213 views

### The ABC conjecture where A and B are smooth

Mochizuki has already claimed to have proven the ABC-conjecture. But even if his claim turns out to be correct the proof will not be easy to understand. With that in mind I'm asking wether anything is ...

**0**

votes

**2**answers

142 views

### Bounds on the counting function for almost-primes

Let $P_k$ be the set of integers with at most $k$ prime factors (counting with multiplicity, say). There is an almost-prime number theorem which gives asymptotic estimates of the size of $P_k$, and ...

**2**

votes

**0**answers

55 views

### Equidistribution of Brillouin zones

Answering the question about Limiting shape for Brillouin zones Victor Kleptsyn proved that $N$th Brillouin zone is very close to a circle of radius $c\sqrt N$ (you can find all necessary definitions ...

**6**

votes

**1**answer

220 views

### Subsets of [1..N] with no three-term arithmetic progressions and no large gaps

Let S be a subset of [1..N] containing no three-term arithmetic progression, and let h(S) be the size of the largest gap between two consecutive elements of S. By Roth's theorem, h(S) has to grow ...

**2**

votes

**1**answer

281 views

### infinite product of (1-1/(p+1)) over a density 0 set of primes

Let $S$ be a density zero set rational primes, in the concrete situation
$\#\{p<X,p\in S\}=\mathcal{O}(x/(\log x)^{3/2-\delta})$ for all $\delta>0$.
Then can $\prod_{p\in S}(1-\frac{1}{p+1})$ ...

**1**

vote

**0**answers

104 views

### Are these quaternion algebras definite or indefinite?

By investigating a different problem I have ended up looking at Quaternion algebras and have a lot to learn about them. Before I do, however, I want to see if my idea has any hope of being useful. So ...

**2**

votes

**2**answers

340 views

### Is there a nice generating function proof of the following identity?

Consider the Jordan function $J_2(n)$ defined by
$$
J_2(n) = \#\{x \in (\mathbb{Z}/n)^2 \mid ord(x) = n\}
$$
(this is OEIS A007434). One can prove the following identity pretty easily:
$$
\sum_{d \mid ...

**1**

vote

**0**answers

52 views

### Calculating Mahler Coefficients

Assume $p$ be prime number ($p>2$), and let $u$ be any topological generator of the group $1 + p \mathbb{Z}_p$ (an open subgroup of the group of units $\mathbb{Z}_p^\times$ of the ring of $p$-adic ...

**4**

votes

**1**answer

378 views

### About factorization in Zhang's proof of weak Twin Prime conjecture

Why does it need to firstly factorize the number n into two factors q and r( Lemma 4 in the paper,see the following)? What's the motivation. What if it doesn't do this factorization?

**0**

votes

**1**answer

90 views

### Sum of digits of a power [closed]

Are there any explicit formula for a sum of digits for a power in the given base? A problem to be specific: find a sum of digits for a number $2^{100}$ in the system with a base 5. In the system with ...

**5**

votes

**1**answer

166 views

### are the coarse moduli schemes of finite etale covers of $\mathcal{M}_{1,1}$ smooth?

Let$\newcommand{\mM}{\mathcal{M}}$ $\mM_{1,1}$ be the moduli stack of elliptic curves. Let $R$ be a Dedekind domain, say $\mathbb{Z}[1/N]$ for simplicity, and suppose we have a finite etale cover:
...

**0**

votes

**2**answers

274 views

### Does theta(n)<n for all n imply the Riemann Hypothesis and/or vice versa?

I know that better and better bounds of the Chebyshev Theta and Psi functions are implied by knowing that the first (insert large number here) zeta zeroes lie on the Critical Line. These bounds, ...

**2**

votes

**0**answers

116 views

### On sets of coprime numbers

We know that from prime number theorem that the number of primes below $n$ and above $\frac n2$ (denoted by $\pi_{n,\frac n2}$ is approximately $$\pi_{n,\frac n2}\approx\frac{n}{2\ln n}.$$
Denote by ...

**1**

vote

**0**answers

57 views

### The genus of specialization of rational surface (compared to genus of parametrization)

Let $f(u,v),g(u,v),h(u,v)$ be polynomials with rational
coefficients or rational functions.
Assume (this happens in general) they parametrize
rational surface $F(x,y,z)=0$.
For rational $a$, assume ...

**2**

votes

**1**answer

204 views

### Reducibility of resultants

This is closely related to this question. Suppose I have the resultant $\mathcal{R}$ of two (or more polynomials) over $\mathbb{Q},$ and suppose $\mathcal{R}$ is not irreducible. What is the ...

**3**

votes

**2**answers

527 views

### What are the necessary conditions for a real number to be a cyclotomic integers？

The motivation of the question is that I try to test when a real number is not an cyclotomic integers. Or more specifically, when a positive real number is not a quantum dimension of a unitary fusion ...

**-2**

votes

**0**answers

112 views

### Upper bound for the exponent $\beta$ of the log in $p_{n+1}-p_{n}\ll \log^{\beta} p_{n}$

Assuming $\beta:=\inf\{C\mid p_{n+1}-p_{n}\ll\log^{C}p_{n}\}<\infty$, can we give an explicit upper bound for $\beta$ ?
Many thanks in advance.

**1**

vote

**1**answer

172 views

### Finding integer representation as difference of two triangular numbers

Since $n = \frac{n(n+1)}{2}-\frac{n(n-1)}{2}$, every natural number can be represented as the difference of two triangular numbers:
$ n = \frac{a(a+1)}{2}-\frac{b(b-1)}{2}$. Finding such a ...

**9**

votes

**2**answers

438 views

### Why going to number fields in number field sieve help beat quadratic sieve?

To factor an $n$ bit integer number field sieve roughly takes $$e^{c{(\ln\ln n)^{\frac23}}({\ln n})^{\frac13}}$$ time while quadratic sieve takes $$e^{c{(\ln\ln n)^{\frac12}}({\ln n})^{\frac12}}$$ ...

**2**

votes

**1**answer

141 views

### Gap between semiprimes

Is there a conjectured gap between semiprimes?
There is a conjectured gap between primes in form of Cramer's conjecture. Using this we have $p_1\leq p_0+c(\log p_0)^2$ for consecutive primes $p_0$ ...

**9**

votes

**1**answer

259 views

### Non-algebraic Hecke characters

Algebraic Hecke characters are ubiquitous in modern number theory. They are in 1-1 correspondence with one dimensional complex Galois representations, and in some precise sense they are the building ...

**10**

votes

**1**answer

441 views

### How much can an Eisenstein series be truncated?

For ease of exposition, I will stick to the simplest case: consider the Eisenstein series for $SL_2(\bf R)$
$$E(z,s)=\sum_{\gamma\in P_{\bf Z}\backslash SL_2(\bf Z)}\text{Im}(\gamma ...

**7**

votes

**4**answers

314 views

### $p$-th Fourier coefficients of newforms of level $\Gamma_1(N)$ with $p|N$

Let $f$ be a newform of level $\Gamma_1(N)$ and character $\chi$ which is not induced by a character mod $N/p$. I learned from these notes by Ribet and Stein that $|a_p|=p^{(k-1)/2}$ where $k$ is the ...

**3**

votes

**1**answer

129 views

### infinite solution of a diophantine quadratic equations

Let $a,b,c,d$ be integers such that $GCD(a,b,c,d)=1$. Assume that the diophantine equation $ax^2+bxy+cxz+dyz-x=0$ has a non-zero solution.Can we assert that it admits infinitely many solutions?
...

**6**

votes

**1**answer

142 views

### power sums and formal divisibility by the Euler totient function

For integers $s \geq 0$ and $n \geq 1$ let $\sigma_s(n) := 1^s + \dots + n^s$ and let
\begin{equation} \sigma_s^*(n) \ : = \ \sum_{\stackrel{\scriptstyle 1 \, \leq \, m \, \leq \, n}{\text{gcd}(m,n) ...

**6**

votes

**1**answer

315 views

### what are the finite etale covers of $\mathbb{Z}_p((x))$?

Let $R$ be the ring of integers of some $p$-adic field $K$ (finite over $\mathbb{Q}_p$) with uniformizer $\pi$ and residue field $k$. I'd like to understand the finite etale extensions of $R((x)) := ...

**2**

votes

**0**answers

91 views

### Residual Representation of a Motive

Suppose we have $M$ a hypergeometric motive, and $\rho$ its associated Galois rep over $\mathbb{Q}_{l}$. Is there any easy/concrete way to find $\bar{\rho}$, the residual representation at a prime (in ...

**28**

votes

**3**answers

1k views

### irreducibility of discriminant

This must be well-known to everyone but me, but here goes: take a general (monic) polynomial $p(x) = x^d + a_{d-1} x^{d-1} + \dotsc + a_0.$ The discriminant is a polynomial $D(a_0, \dotsc, a_{d-1}).$ ...

**2**

votes

**0**answers

208 views

### Generalized Ramanujan's identity with hyperbolic cotangent

Three weeks ago I derived an identity, which generalizes Ramanujan's identity with hyperbolic cotangent. Don't you know is it original or not?
$$
\sum_{n=1}^\infty \frac{\coth(\pi ...

**10**

votes

**2**answers

464 views

### Computing millions of coefficients of non self-dual modular forms

To test some conjectures made by some colleagues, I need to compute millions of coefficients of non self-dual modular forms, preferably in low weight (say 2 or 3). A form such as this.
For elliptic ...

**-2**

votes

**0**answers

65 views

### Findnig the k-th Maximum of a set of real numbers algebraically [migrated]

I am interested in learning more about Theorem 1-4 in the following link:
Optimization in integers and related extremal problems.
Edit: In case your browser is blocking the link for some reason, the ...