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12 votes
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Sieve bound for prime $k$-tuples

Let $d_1<d_2<\dots<d_k$ be integers. Then the number of integers $n\leq x$, such that $n+d_1, n+d_2, \ldots, n+d_k$ are simultaneously prime, is bounded above by $$ \mathfrak{S}(d_1, \ldots, ...
Jan-Christoph Schlage-Puchta's user avatar
10 votes
0 answers
350 views

Are there are any attempts utilising sieve theory to attack the general $a p \pm 1$ problem?

It is currently an open question if there are infinitely many primes $p$ such that $2p + 1$ is prime (Sophie Germain primes) or that at least one of $24p \pm 1$ is prime. Could Zhang's method, or the ...
KStar's user avatar
  • 533
6 votes
0 answers
233 views

admissible tuples vs. prime tuples

Let $\rho^\ast(x)$ denote the maximal length of an admissible sequence in $[1,x]$, i.e. of a sequence which does not cover all the residue classes modulo any $n\geq 2$. Hensley and Richards (1974) ...
GH from MO's user avatar
  • 105k
6 votes
0 answers
296 views

Constants for Rosser's Sieve

I am trying to apply Iwaniec's formulation of Rosser's sieve (here) to obtain nontrivial lower bounds for almost-primes in various sequences. These sequences have sieve dimension 1 (if $g(p)$ is the ...
Xiaoyu He's user avatar
  • 1,161
6 votes
0 answers
505 views

$x^2+1$ attaining almost prime values

Iwaniec, using the linear sieve, proved that $n^2+1$ can be a product of at most two primes infinitely often and furthermore a lower bound of the correct order of magnitude for the number of such ...
Dr. Pi's user avatar
  • 3,062
5 votes
0 answers
326 views

Counting primes, twin primes, cousin primes: unusual approach, connection to some conjectures

I am investigating the following sieve-like algorithm. Let $S_N=\{1,\dots,N\}$. For all primes $p$ with $p_0\leq p \leq M$, we remove from $S_N$ the following elements: all numbers $n\in S_N$ such ...
Vincent Granville's user avatar
5 votes
0 answers
130 views

On Ford's "The distribution of integers with a divisor in a given interval"

Let $H(x,y,z)$ denote the number of positive integers of size at most $x$ which have a divisor in the range $(y,z]$. In his famous "The distribution of integers with a divisor in a given interval&...
Kurisuto Asutora's user avatar
5 votes
0 answers
408 views

Paging Henryk Iwaniec: Problems In Lemma 1?

I gritted my teeth and dove into some sieve theory. In his 1978 article On the Problem of Jacobsthal in Demonstratio Mathematica, Iwaniec presents two Lemmas to prove his main result (leading to $j(n)...
Gerhard Paseman's user avatar
4 votes
0 answers
174 views

Counting number of primes $p$ less than $x$ with certain constraints on prime divisors of $p-1$ for Artin's Conjecture on primitive root

I was reading this paper. There is a Lemma 1 saying that for a fixed prime $q$ the cardinality of the set $\{p \leq x \mid (\frac{q}{p})=-1\}$ such that all odd prime divisors of $p-1$ are greater ...
dragoboy's user avatar
  • 521
4 votes
0 answers
163 views

Large Gaps Between Almost Primes

What is the best lower bound for the longest interval contained in $[1,x]$ free of primes and products of two primes? In other words I am asking for the best lower bounds in a variant of the ...
George Shakan's user avatar
3 votes
0 answers
76 views

Divisor of given order in short intervals

Is the following Open question or Conjecture already known, or eventually settled ? Open question : For sufficiently large $x$ there is at least a positive integer in the interval $[x,x+\log^2(x)]$ ...
G. Melfi's user avatar
  • 433
3 votes
0 answers
232 views

Numbers made up of primes from a given set

Take a set $\mathcal P$ of primes and denote by $\langle \mathcal P\rangle $ the set of all natural numbers composed of primes from $\mathcal P$. If \[ \sum _{p\in \mathcal P}\frac {1}{p}\] converges ...
tomos's user avatar
  • 1,381
3 votes
0 answers
252 views

Counting twin primes with a sieve-like algorithm

The sequence A002822, denoted as $S$, represents all the twin primes except $\{3, 5\}$. Other than that exception, $k$ and $k+2$ are twin primes iff $(k+1)/6\in S$. Let $S(N)$ be the subset of $S$ ...
Vincent Granville's user avatar
3 votes
0 answers
173 views

Kubilius model in higher sieve dimension?

The Kubilius model, based on the fundamental lemma of sieve theory, let us approximate the probability of events depending on the variables $X_p$, $p\leq y$, where $X_p=1$ if $p|n$ ($n$ a random ...
H A Helfgott's user avatar
  • 20.2k
3 votes
0 answers
106 views

Friedlander-Iwaniec Flipping moduli

I am reading section 12 (Flipping Moduli) of the paper "The polynomial $X^2+Y^4$ captures its primes" by Friedlander and Iwaniec. At page 997, just below equation (12.7) we start estimating the ...
user133643's user avatar
3 votes
0 answers
205 views

Sum of multiplicative arithmetic function over squarefree numbers

In the "Sieve methods" notes of Dimitris Koukoulopoulos (see http://www.dms.umontreal.ca/~koukoulo/documents/notes/sievemethods.pdf), the following useful result can be found: Theorem 0.4.1. Let $g$ ...
user avatar
3 votes
0 answers
97 views

A sieve result with two parameters

I proved the following sieve result and - since the proof is quite long and I need to use it in a work - I am looking for a reference to it (or at least something from which it could be proved quickly)...
user avatar
3 votes
0 answers
603 views

Ramanujan conjecture and covariance of Kloosterman sums

There has been interest in moments and covariances/correlations of Kloosterman sums $S(m,n,c)=\sum_{ad=1\ (\text{mod}\ c)} e(\frac{ma+nd}{c})$ like $\sum_{m\in\mathbb F_c} S(m,n,c)^k$, $\sum\sum_{m_1,...
plm's user avatar
  • 982
2 votes
1 answer
227 views

Sieve Method works for variant question?

There are multiple results on the sieve method, and I wanted to ask about the following variant (to know if it is trivial by one of the current versions of the sieve method, or seems a challenging ...
Stijn Cambie's user avatar
2 votes
0 answers
179 views

A Brun-Titchmarsh type result for divisor sums; asymptotic/improved bound

In Shiu's work ('A Brun-Titchmarsh theorem for multiplicative functions') he proved that if $r\le x$ is a natural number, we have $$\sum_{r<n\le x}d(n)d(n-r)\ll x\log^2x\sum_{d|r}\frac{1}{d}.$$ I ...
user avatar
2 votes
0 answers
119 views

Almost-prime values attained by polynomials, with extra conditions

Given integers $a_1,\ldots,a_k>0$ and $b_1,\ldots,b_k$, consider the polynomial $f(x) = \prod_{i=1}^{k} (a_i x +b_i) \in \mathbb{Z}[x]$. Suppose that $\{ a_i x+b_i\}_{i=1}^{k}$ are pairwise ...
Ofir Gorodetsky's user avatar
2 votes
0 answers
120 views

Sieving the values of an arithmetic sequence which is infinitely many times $1$

I have a sequence of positive integers $a_n$ which assumes infinitely many times the value $1$. I want to estimate the cardinality of the following set: $$\#\{n\leq x : a_n>1 \text{ and } (a_n, \...
The Number Theorist's user avatar
2 votes
0 answers
189 views

Lattice Sieving in Number Field Sieve

I am currently going through Pollard's article on Lattice Sieving and have a few confusions. Firstly, how to figure that $C$ and $D$ in the two-dimensional array so that every $(c,d)$ pair corresponds ...
swati setia's user avatar
1 vote
0 answers
192 views

Prerequisites for Chen's theorem?

I am an undergraduate theoretical physics student, and I am trying to understand Chen's theorem. But when I tried to read Chen Jingrun's 1973 paper (https://www.sciengine.com/Math%20A0/doi/10.1360/...
Ben's user avatar
  • 11
1 vote
0 answers
95 views

Sieve theory obstruction: prime-sparse and nearly full-differenced sets?

Let $D(A) = {|a-b| : a, b \in A}$ denote the difference set of $A \subseteq \mathbb{Z}$. A set $A \subseteq (x/2, x]$ is almost full-differenced if $|D(A)| \geq \frac{x}{2} - \log x$. Let $C_x$ denote ...
Ganesh Gayatri's user avatar
1 vote
0 answers
148 views

Counting prime factors of polynomial functions

Let $\Omega(n)$ denote the number of prime factors (counted with multiplicity) of a non-zero integer $n$. For $f \in \mathbb Z[X]$ non-zero, let $$m(f) = \liminf_{n \to \infty} \Omega(f(n))$$ (1) Is $...
Jens Reinhold's user avatar
1 vote
0 answers
94 views

Large sieve inequality-like sum without the square

Let $S(\alpha) = \sum_{n\leq N} w(n) e^{2\pi i \alpha n}$ for some function $w$ defined on $\mathbb{R}$. Suppose $\alpha_1, \ldots, \alpha_R$ are real numbers that are $\delta$-spaced modulo $1$, for ...
SJY's user avatar
  • 579
1 vote
0 answers
106 views

Sieve Theory uniform bound in Richert's Lectures on Sieves

I'm not sure how suitable this question is, but I have had no response on Mathematics Stack Exchange. My original question is here: https://math.stackexchange.com/questions/3402938/uniformity-...
VBACODER's user avatar
  • 111
1 vote
0 answers
139 views

Sieving question

How many integers $n\leq X$ are there with the property that $\prod_{p\in S} p \geq n^{1/2-\epsilon}$? Here (to keep notation readable) I've written $p\in S$ if and only if $p||n$ (that is, $p|n$ and $...
alpoge's user avatar
  • 793
0 votes
0 answers
54 views

On the upper bound estimation of $D(N)$ in Chen Jingrun's theorem

What are the current research results on the estimation of the upper bound of $D(N)$ in Chen Jingrun's theorem? Including but not limited to Chen Jingrun's improvement 7.8342 and Wu Jie's improvement ...
RL433's user avatar
  • 1
0 votes
0 answers
183 views

Prime counting function estimate sieve of Eratosthenes-Legendre

I'm trying to arrive at estimate 1.17 (page 21) of Koukoulopoulos lecture notes [https://dms.umontreal.ca/~koukoulo/documents/notes/sievemethods.pdf] $$\#\{n \leq x : p|n \Rightarrow p > \sqrt{x}\}...
numbertheorylearner's user avatar