The moments of split greatest common divisors

Fuente: arXiv
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Main Authors: Jha, Abhishek, Nath, Ayan, Tron, Emanuele
Format: Preprint
Published: 2024
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_version_ 1866916358209404928
author Jha, Abhishek
Nath, Ayan
Tron, Emanuele
author_facet Jha, Abhishek
Nath, Ayan
Tron, Emanuele
contents Sequences of the form $(\gcd(u_n,v_n))_{n \in \mathbb N}$, with $(u_n)_n$, $(v_n)_n$ sums of $S$-units, have been considered by several authors. The study of $\gcd(n,u_n)$ corresponds, following Silverman, to divisibility sequences arising from the split algebraic group $\mathbb G_{\mathrm{a}} \times \mathbb G_{\mathrm{m}}$; in this case, Sanna determined all asymptotic moments of the arithmetic function $\log\,\gcd (n,u_n)$ when $(u_n)_n$ is a Lucas sequence. Here, we characterize the asymptotic behavior of the moments themselves $\sum_{n \leq x}\,\gcd(n,u_n)^λ$, thus solving the moment problem for $\mathbb G_{\mathrm{a}} \times \mathbb G_{\mathrm{m}}$. We give both unconditional and conditional results, the latter only relying on standard conjectures in analytic number theory.
format Preprint
id arxiv_https___arxiv_org_abs_2408_05820
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The moments of split greatest common divisors
Jha, Abhishek
Nath, Ayan
Tron, Emanuele
Number Theory
11N56, 11B37
Sequences of the form $(\gcd(u_n,v_n))_{n \in \mathbb N}$, with $(u_n)_n$, $(v_n)_n$ sums of $S$-units, have been considered by several authors. The study of $\gcd(n,u_n)$ corresponds, following Silverman, to divisibility sequences arising from the split algebraic group $\mathbb G_{\mathrm{a}} \times \mathbb G_{\mathrm{m}}$; in this case, Sanna determined all asymptotic moments of the arithmetic function $\log\,\gcd (n,u_n)$ when $(u_n)_n$ is a Lucas sequence. Here, we characterize the asymptotic behavior of the moments themselves $\sum_{n \leq x}\,\gcd(n,u_n)^λ$, thus solving the moment problem for $\mathbb G_{\mathrm{a}} \times \mathbb G_{\mathrm{m}}$. We give both unconditional and conditional results, the latter only relying on standard conjectures in analytic number theory.
title The moments of split greatest common divisors
topic Number Theory
11N56, 11B37
url https://arxiv.org/abs/2408.05820