On infinite arithmetic progressions in sumsets

Let k be a positive integer.Denote by D_1/k the least integer d such that for every set A of nonnegative integers with the lower density 1/k,the set(k+1)A contains an infinite arithmetic progression with difference at most d,where(k+1)A is the set of all sums of k+1 elements(not necessarily distinct) of A.Chen and Li(2019) conjectured that D_1/k=k²+o(k²).The purpose of this paper is to confirm the above conjecture.We also prove that D_1/k is a ...     

关于算术级数的幂次和

主要研究了ζ函数关于模 q剩余类部分和,不仅得出了一个重要的渐近公式,而且将Kubert恒等式推广到赫尔维茨ζ函数、欧拉双Γ函数和贝努利多项式上.     

On arithmetic progressions on Pellian equations

We consider arithmetic progressions consisting of integers which are y-components of solutions of an equation of the form x ² ? dy ² = m. We show that for almost all four-term arithmetic progressions such an equation exists. We construct a seven-term arithmetic progression with the given property, and also several five-term arithmetic progressions which satisfy two different equations of the given form. These results are obtained by studying the properties of a parametric family of elliptic curves.     

On the distribution of square-full numbers in arithmetic progressions

A positive integer n is called a square-full number if p ² divides n whenever p is a prime divisor of n. In this paper we study the distribution of square-full numbers in arithmetic progressions by using the properties of Riemann zeta functions and Dirichlet L-functions.     

On the maximal length of two sequences of integers in arithmetic progressions with the same prime divisors

In this paper we consider an analogue of the problem of Erds and Woods for arithmetic progressions. A positive answer follows from theabc conjecture. Partial results are obtained unconditionally.     

Discrepancy in arithmetic progressions

It is proven that there is a two-coloring of the first integers for which all arithmetic progressions have discrepancy less than . This shows that a 1964 result of K. F. Roth is, up to constants, best possible.

     

Powerful arithmetic progressions

We give a complete characterization of so-called powerful arithmetic progressions, i.e. of progressions whose kth term is a kth power for all k. We also prove that the length of any primitive arithmetic progression of powers can be bounded both by any term of the progression different from 0 and ±1, and by its common difference. In particular, such a progression can have only finite length.     

Primes in arithmetic progressions

Strengthening work of Rosser, Schoenfeld, and McCurley, we establish explicit Chebyshev-type estimates in the prime number theorem for arithmetic progressions, for all moduli and other small moduli.

     

On products of consecutive arithmetic progressions. II

Let \({f(x, k, d) = x(x + d)\cdots(x + (k - 1)d)}\) be a polynomial with \({k \geq 2}\), \({d \geq 1}\). We consider the Diophantine equation \({\prod_{i = 1}^{r} f(x_i, k_i, d) = y^2}\), which is inspired by a question of Erd?s and Graham [4, p. 67]. Using the theory of Pellian equation, we give infinitely many (nontrivial) positive integer solutions of the above Diophantine equation for some cases.     

On the intersection of infinite geometric and arithmetic progressions

We prove that the intersection G ∩ A of an infinite geometric progression G = u, uq, uq ², uq ³, ..., where u > 0 and q > 1 are real numbers, and an infinite arithmetic progression A contains at most 3 elements except for two kinds of ratios q. The first exception occurs for q = r ^1/d , where r > 1 is a rational number and d ∈ ℕ. Then this intersection can be of any cardinality s ∈ ℕ or infinite. The other (possible) exception may occur for q = β ^1/d , where β > 1 is a real cubic algebraic number with two nonreal conjugates of moduli distinct from β and d ∈ ℕ. In this (cubic) case, we prove that the intersection G ∩ A contains at most 6 elements.     

On some Rado numbers for generalized arithmetic progressions

The 2-color Rado number for the equation x₁+x₂−2x₃=c, which for each constant we denote by S₁(c), is the least integer, if it exists, such that every 2-coloring, Δ : [1,S₁(c)]→{0,1}, of the natural numbers admits a monochromatic solution to x₁+x₂−2x₃=c, and otherwise S₁(c)=∞. We determine the 2-color Rado number for the equation x₁+x₂−2x₃=c, when additional inequality restraints on the variables are added. In particular, the case where we require x₂<x₃<x₁, is a generalization of the 3-term arithmetic progression; and the work done here improves previously established upper bounds to an exact value.     

Discrepancy in generalized arithmetic progressions

Estimating the discrepancy of the set of all arithmetic progressions in the first N natural numbers was one of the famous open problems in combinatorial discrepancy theory for a long time, successfully solved by K. Roth (lower bound) and Beck (upper bound). They proved that D(N)=min_χmax_A|∑_xAχ(x)|=Θ(N^1/4), where the minimum is taken over all colorings χ:[N]→{−1,1} and the maximum over all arithmetic progressions in [N]={0,…,N−1}.Sumsets of k arithmetic progressions, A₁++A_k, are called k-arithmetic progressions and they are important objects in additive combinatorics. We define D_k(N) as the discrepancy of the set {P∩[N]:P is a k-arithmetic progression}. The second author proved that D_k(N)=Ω(N^k/(2k+2)) and Přívětivý improved it to Ω(N^1/2) for all k≥3. Since the probabilistic argument gives D_k(N)=O((NlogN)^1/2) for all fixed k, the case k=2 remained the only case with a large gap between the known upper and lower bounds. We bridge this gap (up to a logarithmic factor) by proving that D_k(N)=Ω(N^1/2) for all k≥2.Indeed we prove the multicolor version of this result.     

On the index of fractions with square-free denominators in arithmetic progressions

We prove asymptotic formulas for the first and second moments of the index of fractions with square-free denominators of order Q streaming in a given arithmetic progression as Q→∞. A. Zaharescu was supported by NSF grant number DMS-0456615. This research was also partially supported by the CERES Program 4-147/2004 of the Romanian Ministry of Education and Research.     

On products of primes and almost primes in arithmetic progressions

We show that for any integers a and m with m ≥ 1 and gcd(a,m) = 1, there is a solution to the congruence pr ≡ a (modm) where p is prime, r is a product of at most k = 17 prime factors and p, r ≤ m. This is a relaxed version of the still open question, studied by P. Erd?s, A. M. Odlyzko and A. Sárközy, that corresponds to k = 1 (that is, to products of two primes).