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JOURNALS // Chebyshevskii Sbornik // Archive

Chebyshevskii Sb., 2022 Volume 23, Issue 5, Pages 145–151 (Mi cheb1261)

BRIEF MESSAGES

On the intersection of two homogeneous Beatty sequences

A. V. Begunts, D. V. Goryashin

Lomonosov Moscow State University (Moscow)

Abstract: Homogeneous Beatty sequences are sequences of the form $a_n=[\alpha n]$, where $\alpha$ is a positive irrational number. In 1957 T. Skolem showed that if the numbers $1,\frac{1}{\alpha},\frac{1}{\beta}$ are linearly independent over the field of rational numbers, then the sequences $[\alpha n]$ and $[\beta n]$ have infinitely many elements in common. T. Bang strengthened this result: denote $S_{\alpha,\beta}(N)$ the number of natural numbers $k$, $1\leqslant k\leqslant N$, that belong to both Beatty sequences $[\alpha n]$, $[\beta m]$, and the numbers $1,\frac{1}{\alpha},\frac{1}{\beta}$ are linearly independent over the field of rational numbers, then $S_{\alpha,\beta}(N)\sim \frac{N}{\alpha\beta}$ for $N\to\infty.$
In this paper, we prove a refinement of this result for the case of algebraic numbers. Let $\alpha,\beta>1$ be irrational algebraic numbers such that $1,\frac{1}{\alpha},\frac{1}{\beta}$ are linearly independent over the field of rational numbers. Then for any $\varepsilon>0$ the following asymptotic formula holds:
$$S_{\alpha,\beta}(N)=\frac{N}{\alpha\beta}+O\bigl(N^{\frac12+\varepsilon}\bigr), N\to\infty.$$


Keywords: homogeneous Beatty sequence, exponential sums, asymptotic formula.

UDC: 511.35, 517.15

Received: 15.06.2022
Accepted: 22.12.2022

DOI: 10.22405/2226-8383-2022-23-5-145-151



© Steklov Math. Inst. of RAS, 2025