On a Variant of Pillai's problem involving convergent denominators of quadratic irrationals

Fuente: arXiv
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Main Author: Mittal, Mohit
Format: Preprint
Published: 2025
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author Mittal, Mohit
author_facet Mittal, Mohit
contents Let $(q_{α, n})_{n \geq 0}$ be the sequence of convergent denominators to the simple continued fraction expansion of $α$. For certain specific choices of $α$, this sequence is a Lehmer sequence. In this paper, we show that there are only finitely many integers $c$ such that the equation $q_{α, n} - q_{β, m} = c$ has at least two distinct solutions $(n,m)$, where $α,β$ are quadratic irrationals with $\mathbb{Q}(α)\neq \mathbb{Q}(β)$. In specific instances, we solve the equation $q_{α, n} - q_{β, m} = c$ completely and explicitly list all solutions.
format Preprint
id arxiv_https___arxiv_org_abs_2508_11243
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On a Variant of Pillai's problem involving convergent denominators of quadratic irrationals
Mittal, Mohit
Number Theory
11D45, 11D61, 11J86, 11R04, 11R11
Let $(q_{α, n})_{n \geq 0}$ be the sequence of convergent denominators to the simple continued fraction expansion of $α$. For certain specific choices of $α$, this sequence is a Lehmer sequence. In this paper, we show that there are only finitely many integers $c$ such that the equation $q_{α, n} - q_{β, m} = c$ has at least two distinct solutions $(n,m)$, where $α,β$ are quadratic irrationals with $\mathbb{Q}(α)\neq \mathbb{Q}(β)$. In specific instances, we solve the equation $q_{α, n} - q_{β, m} = c$ completely and explicitly list all solutions.
title On a Variant of Pillai's problem involving convergent denominators of quadratic irrationals
topic Number Theory
11D45, 11D61, 11J86, 11R04, 11R11
url https://arxiv.org/abs/2508.11243