The joint distribution of binary and ternary digits sums

Fuente: arXiv
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Auteurs principaux: Drmota, Michael, Spiegelhofer, Lukas
Format: Preprint
Publié: 2025
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author Drmota, Michael
Spiegelhofer, Lukas
author_facet Drmota, Michael
Spiegelhofer, Lukas
contents We consider the sum-of-digits functions $s_2$ and $s_3$ in bases $2$ and $3$. These functions just return the minimal numbers of powers of two (resp. three) needed in order to represent a nonnegative integer as their sum. A result of the second author states that there are infinitely many \emph{collisions} of $s_2$ and $s_3$, that is, positive integers $n$ such that \[s_2(n)=s_3(n).\] This resolved a long-standing folklore conjecture. In the present paper, we prove a strong generalization of this statement, stating that $(s_2(n),s_3(n))$ attains almost all values in $\mathbb N^2$, in the sense of asymptotic density. In particular, this yields \emph{generalized collisions}: for any pair $(a,b)$ of positive integers, the equation \[as_2(n)=bs_3(n)\] admits infinitely many solutions in $n$.
format Preprint
id arxiv_https___arxiv_org_abs_2501_00850
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The joint distribution of binary and ternary digits sums
Drmota, Michael
Spiegelhofer, Lukas
Number Theory
Primary: 11A63, Secondary: 11N60
We consider the sum-of-digits functions $s_2$ and $s_3$ in bases $2$ and $3$. These functions just return the minimal numbers of powers of two (resp. three) needed in order to represent a nonnegative integer as their sum. A result of the second author states that there are infinitely many \emph{collisions} of $s_2$ and $s_3$, that is, positive integers $n$ such that \[s_2(n)=s_3(n).\] This resolved a long-standing folklore conjecture. In the present paper, we prove a strong generalization of this statement, stating that $(s_2(n),s_3(n))$ attains almost all values in $\mathbb N^2$, in the sense of asymptotic density. In particular, this yields \emph{generalized collisions}: for any pair $(a,b)$ of positive integers, the equation \[as_2(n)=bs_3(n)\] admits infinitely many solutions in $n$.
title The joint distribution of binary and ternary digits sums
topic Number Theory
Primary: 11A63, Secondary: 11N60
url https://arxiv.org/abs/2501.00850