# Questions tagged [nt.number-theory]

Prime numbers, diophantine equations, diophantine approximations, analytic or algebraic number theory, arithmetic geometry, Galois theory, transcendental number theory, continued fractions

10,465 questions

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154 views

### A conjectural lower bound for $|\{\sum_{k=1}^nka_k:\ a_1,\ldots,a_n\ \text{are distinct elements of }\ A\}|$

Motivated by Question 315568 of mine, I'm interested in the set
$$S(n):=\bigg\{\sum_{k=1}^n k\pi(k):\ \pi\in S_n\bigg\}.$$
It is easy to see that
$$S(1)=\{1\},\ S(2)=\{4,5\}\ \text{and}\ S(3)=\{10,...

**2**

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196 views

### Algebraically independent vectors in tensor product

$\mathcal L$ and $\mathcal L'$ be full rank lattices in $\mathbb R^n$ with shortest vectors $v_1,\dots,v_n$ and $v_1',\dots,v_n'$ respectively where $$\|v_1\|_2\leq\dots\leq\|v_n\|_2$$
$$\|v_1'\|_2\...

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**1**answer

154 views

### Derangements and unit fractions

Motivated by a recent question of Zhi-Wei Sun and its nice answer by Zhao Shen, here are two related questions.
Let $S_n$ be the group of permutations on $\{1, 2, \ldots, n\}$.
a. For each $n \ge ...

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**0**answers

104 views

### Probability of degree $0$ gcd between every pair of random homogeneous polynomials shifted by random primes?

Take $n,d,B\in\mathbb Z_{>0}$ with $d<n$ and denote $\mathcal M_{n,d}$ to be set of all total degree $d$ monomials in $n$ variables $x_1,\dots,x_n$ with degree $\leq1$ in each variable (...

**2**

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**0**answers

86 views

### Coppersmith's method to quadrivariate degree $2$ polynomials that behave as bivariate?

We have a polynomial $f(x_1,x_2,x_3,x_4)\in\mathbb Z[x_1,x_2,x_3,x_4]$ where the only monomials are either from set $$\{x_1,x_1x_2,x_2,x_3,x_3x_4,x_4\}$$ and we seek solutions $(x_1,x_2,x_3,x_4)\in\...

**3**

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193 views

### Is there an analogue for the Balazard et al criterion for the Generalised Riemann Hypothesis?

A nice result of Balazard et al says the Riemann Hypothesis is equivalent to the statement that
$$\int_{-\infty}^{\infty} \frac{\log|\zeta(1/2 + it)|}{\frac{1}{4}+t^2} \mathrm{d}t=0$$ where $\zeta$ ...

**8**

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**3**answers

330 views

### Physical Applications of Locally Symmetric Spaces

Locally Symmetric Spaces are the basis of the Langlands program—a set of ambitious and interconnected conjectures connecting representation theory to number theory, firstly proposed in 1967 by Robert ...

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68 views

### Ideal class groups of real abelian number fields

I have a question from page 13 of Thaine's article on Ideal class groups of real abelian number fields - Annals of Math, 128 (1988).
Here's an attempt to summarize.
Let $W = E/C$ where $E$ is the ...

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79 views

### Probability distribution from equidistribution - II

Pick a random pair $(a,b)\in\mathbb Z_n^2\backslash\{0,0\}$ and denote $N(a,b)$ to be minimum $\ell_2$ norm of vector $(x,y)$ as $(x,y)$ ranges over all non-zero integral solutions to $(x,y)\equiv t(a,...

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50 views

### Method of Coppersmith optimal for multivariate?

It is shown that Coppersmith method yields optimal integer root extraction for univariate polynomials in https://arxiv.org/abs/1605.08065 and a follow up work attempts this for bivariate polynomials ...

**3**

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**1**answer

166 views

### Is there relationship between $\mu=0$ for an elliptic curve and the irreducibility of its residual representation at a prime $p$?

I remember it being mentioned at a talk that if $E$ is an elliptic curve over $\mathbb{Q}$ and $p$ a prime at which it has good reduction then the dual to the Selmer group over the cyclotomic $\mathbb{...

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**1**answer

127 views

### How likely is it for Selmer groups to have mu invariant 0?

Given a number field $K$, how likely is it that we'll find at least one elliptic curve $E/K$ such that the $\mu$-invariant of its Selmer group is 0 (in a cyclotomic extension)?

**4**

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**2**answers

129 views

### Congruence subgroups in arithmetic lattices of $\mathrm{SO}(n,1)$

I am currently reading the paper Deformation Spaces Associated to Hyperbolic Manifolds by Johnson and Millson, Section 7, and the highlighted bit below has been giving me difficulty:
Specifically, ...

**4**

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154 views

### Lower bound for some sums of roots of unity

Let $n$ be a positive integer (assume $n$ is prime for simplicity), and let $x_k = \pm1$, for $k = 0,1,2,..., n-1$. Let $\rho$ be an $n-$th primitive root of unity, I am interested in a lower bound ...

**9**

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**1**answer

338 views

### Nontrivial p-divisible groups over $\mathbb Z$ for general prime $p$

In Tate's famous paper about $p$-divisible groups, for a prime number $p$ he asks whether there exists a $p$-divisible group $G$ over $\mathbb Z$ such that $G$ is not a direct sum of $\mu_{p^\infty}$ ...

**8**

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**1**answer

513 views

### Linear equations in primes

Quoting from Green-Tao, "Linear equations in primes" (especially Cor. 1.9 in https://arxiv.org/pdf/math/0606088.pdf), any system of linear forms of finite complexity and without any local obstructions ...

**6**

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116 views

### Can the partition function $p(n)$ take perfect power values?

Recall that the perfect powers are those integers $m^k$ with $k,m\in\{2,3,\ldots\}$. I don't consider $0$ or $1$ as a perfect power.
Y. Bugeaud, M. Mignotte and S. Siksek [Annals of Math., 2006] ...

**7**

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**1**answer

171 views

### Distribution of $\{cn^a\}$

Assume that $1<a<2$ and $c\ne 0$ is a real number. What is known about the distribution of the sequence $cn^a$ modulo 1? Say, is it true that for certain $\theta<1$ (depending on $a$ and $c$) ...

**7**

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**1**answer

414 views

### Is the sum $\sum_{d\mid n}\frac1{d+1}$ never integral?

Recall that a positive integer $n$ is a perfect number if and only if
$$\frac{\sigma(n)}n=\sum_{d\mid n}\frac1d=2.$$
QUESTION: Is my following conjecture true?
Conjecture. (i) We have $\sum_{d\mid ...

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100 views

### Reference request for bounds of $n$-th composite

Motivation
I will briefly elaborate here my motivations for asking the question. If you are not interested in it then please go to the questions.
Recently during trying to understand and prove the ...

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53 views

### An issue with showing that an Iwasawa module has zero $\mu$ invariant

Let $\chi$ denote the $p$-adic cyclotomic character. Let $\mathbb{Q}^{cyc}$ denote the cyclotomic $\mathbb{Z}_p$-extension of $\mathbb{Q}$. Let $\gamma$ be the topological generator of $\Gamma=\text{...

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**3**answers

572 views

### Question concerning twin primes

The multiplication graphs $p/q$ – with an edge between $a,b$ iff $ap \equiv b\operatorname{mod} q$ – for some twin primes $p$ and $q = p+2$ reveal an astonishing pattern:
$(p+0)/(p+1)$ ...

**3**

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69 views

### Independence of number fields generated by roots of Littlewood polynomials

Let $\mathcal{R}_d \subset \bar{\mathbb{Q}}$ be the set of all roots of degree $d$ polynomials with $\{-1,0,1\}$ coefficients and
$$
c(d) := \min_{\substack{ \alpha, \beta \in \mathcal{R}_d \\ \alpha^...

**2**

votes

**1**answer

164 views

### Does $\det[\lfloor(i^2+j^2)/p\rfloor]_{1\le i,j\le(p-1)/2}$ vanish for each prime $p>7$ with $p\equiv3\pmod4$?

Let $\lfloor x\rfloor$ be the floor function.
QUESTION: Does the determinant
$$D_p=\det\left[\left\lfloor\frac{i^2+j^2}p\right\rfloor\right]_{1\le i,j\le(p-1)/2}$$ vanish for each prime $p>7$ with ...

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130 views

### Find all placement methods are made so that $S=\sum\limits_{1\leq i<j\leq n}|P_iP_j| ^2$ takes the maximum value

A few days ago, China held the Mathematics Olympiad. In this competition, all the students did not do the last question. But what I'm more interested in right now is, what's the background to this ...

**2**

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108 views

### Chen primes and permutations

In 1973 the Chinese mathematician J.-R. Chen proved that there are infinitely many primes $p$ such that $p+2$ is a product of at most two primes. Nowadays such primes $p$ are called Chen primes.
For $...

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86 views

### Roots of unity, vanishing sums and derivatives

Fix integers $n\geqslant1$ and $k\geqslant 0$. For an
integer $i$, the $k$-fold derivative of $x^i$ can be denoted by
$i^{\underline{k}}x^{i-k}$ where $i^{\underline{k}}$ means
$i(i-1)\cdots(i-k+1)$ ...

**19**

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**1**answer

613 views

### Permutations $\pi\in S_n$ with $\sum_{k=1}^n\frac1{k+\pi(k)}=1$

Let $S_n$ be the symmetric group of all the permutations of $\{1,\ldots,n\}$.
Motivated by Question 315568 (http://mathoverflow.net/questions/315568), here I pose the following question.
QUESTION: Is ...

**8**

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**1**answer

136 views

### Index of the endomorphism ring of an abelian surface

For an abelian surface $A/\mathbb{Q}$ such that $R:=\mathrm{End}_{\mathbb{Q}}(A)$ is an order in a real quadratic field $K$ (so a $\mathrm{GL}_2$-type surface), is there a bound on the index $[O_K : R]...

**2**

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84 views

### What is the current status on the corank conjecture for Selmer groups (2)?

This is a follow up to What is the current status on the corank conjecture for Selmer groups?
Let E be an elliptic curve over a number field $K$ an imaginary quadratic field in which a prime $p$ ...

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63 views

### Meyer's class number formulas

In my previous question I asked for a reference for $L$-series of quadratic orders in connection with a certain class number formula. It seems that this had been investigated by Curt Meyer. Is there ...

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118 views

### List of applications of the Deformation theory of Galois Representations in contexts other that $R=T$

The Deformation theory of Galois representations developed by Mazur has been extensively used in proving that Galois representations with special properties are modular/automorphic through the ...

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115 views

### Permutations $\pi\in S_n$ with $p_k+p_{\pi(k)}+1$ prime for all $k=1,\ldots,n$

As usual, let $S_n$ be the symmetric group of all permutations of $\{1,\ldots,n\}$.
QUESTION: Is my following conjecture true?
Conjecture. For any positive integer $n$, there is a permutation $\pi\...

**5**

votes

**1**answer

269 views

### What is the current status on the corank conjecture for Selmer groups?

Let $E$ be an elliptic curve over $\mathbb{Q}$ and $p$ a prime. It is conjectured in the book of Coates and Sujatha "Galois Cohomology of Elliptic Curves" (Conjecture 2.5) that the corank of the ...

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**1**answer

208 views

### Odd permutations $\tau\in S_n$ with $\sum_{k=1}^nk\tau(k)$ an odd square

For any positive integer $n$, as usual we let $S_n$ be the symmetric group of all the permutations of $\{1,\ldots,n\}$.
QUESTION: Is it true that for each integer $n>3$ there is an odd permutation ...

**4**

votes

**1**answer

75 views

### Separate the trivial partition by a linear hyperspace

Let $e=[1,1,\ldots,1]\in\mathbb{Z}^n$. I am looking for a way to find a vector $a\in\mathbb{Z}^n$ such that:
$\langle a,e\rangle=0$ and
for every nonnegative $v\in\mathbb{Z}^n$ such that $\langle e,v\...

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80 views

### Dirichlet series of Euler's totient function for Gaussian integers?

Define the Euler's totient function for Gaussian integers $f:\mathbb Z[i]_{\ne 0}\mapsto \mathbb Z_{>0}$:
$$f(z):=\sum_{\substack{q\in\mathbb Z[i]_{\ne 0}\\|q|\le|z|, |\gcd(q,z)|=1}}1,$$
and the ...

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**2**answers

695 views

### If Goldbach's Conjecture is eventually true, is it necessarily true?

We have all heard that if Goldbach's conjecture is independent, then it is true. This is because if GC is false then there is an even number which is not the sum of two primes, and hence a finite ...

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90 views

### Integer partitions under divisibility constraint

Consider integer partitions of $x \in \mathbb{N}$ of size $k$ under the constraint that the partition elements are distinct and the ratio of any element to each smaller element is a natural number.
...

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**1**answer

191 views

### Integral Tate-Sen theory

Let $K$ be a finite extension of $\mathbb{Q}_p$, and let $C=\widehat{\overline{K}}$ be the completion of the algebraic closure of $K$. Let $\mathscr{O}_C$ be the ring of integers in $C$, and let $G_K$ ...

**31**

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**1**answer

1k views

### Probably true, but provably unprovable

I'm wondering if anyone has found, or can find, a sequence of statements $P(n)$ ($n \in \mathbb{N}$) such that:
Heuristic arguments using probability theory suggest that all the statements $P(n)$ are ...

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99 views

### Is there a (Riemann) explicit formula for $\sum_{p\le x}\frac{1}{p}$ involving a sum over the non-trivial zeros ρ of the Riemann zeta function?

Let $f(x)=\sum_{p\le x}\frac{1}{p}$ and $f_0(x)=\frac{1}{2}(f(x+0)+f(x-0))$. Then is there a (Riemann) explicit formula for $f_0(x)$ involving a sum over the non-trivial zeros ρ of the Riemann zeta ...

**6**

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**1**answer

119 views

### Explaining patterns in modular multiplication graphs

Let the multiplication graph $n/m$ be the graph with $m$ points distributed evenly on a circle and a line between two points $a$, $b$ when $an \equiv b\operatorname{mod} m$.
These graphs often look ...

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79 views

### How to determine the unramified character corresponding to an unramified Langlands parameter?

Let $F$ be a p-adic field with ring of integers $\mathcal{O}$. Let $\textbf{G}$ be a connected split reductive algebraic group over $F$. For simplicity, we assume that $\textbf{G}$ is a Chevalley ...

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218 views

### Easy cases of Herbrand's theorem

$\def\QQ{\mathbb{Q}}\def\ZZ{\mathbb{Z}}$ I recall Herbrand's theorem about class groups of cyclotomic fields: Let $p$ be an odd prime, let $\zeta$ be a primitive $p$-th root of $1$ and let $K = \QQ(\...

**15**

votes

**5**answers

1k views

### Sum of the reciprocals of radicals

Recall that the radical of an integer $n$ is defined to be $\operatorname{rad}(n) = \prod_{p \mid n } p$.
For a paper, I need the result that
$$\sum_{n \leq x} \frac{1}{\operatorname{rad}(n)} \ll_\...

**5**

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**0**answers

115 views

### A relation concerning the “sum of squares” counting function $r_2(n)$

This is a re-post from MSE as I did not get any response there.
Let $r_2(n)$ denote the number of ways in which a positive integer $n$ can be expressed as the sum of squares of two integers. Here ...

**17**

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**1**answer

2k views

### A mysterious connection between primes and squares

Motivated by two previous questions of mine (cf. Primes arising from permutations and Primes arising from permutations (II)), here I ask a curious question which connects primes with squares.
...

**7**

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**0**answers

158 views

### Number fields ordered by discriminant

Since the discriminant of a number field $K \neq \mathbb{Q}$ is bounded from below by an exponential of the degree $[K:\mathbb{Q}]$, for instance by Minkowski's Geometry of Numbers bound, there are ...

**3**

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**0**answers

262 views

### Primes arising from permutations (II)

In Question 315259 (cf. Primes arising from permutations) I asked a question on primes arising from permutations which looks quite challenging.
Here I pose a new question in this direction which does ...