On the behavior of binary block-counting functions under addition

Fuente: arXiv
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Main Author: Sobolewski, Bartosz
Format: Preprint
Published: 2024
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author Sobolewski, Bartosz
author_facet Sobolewski, Bartosz
contents Let $\mathsf{s}(n)$ denote the sum of binary digits of an integer $n \geq 0$. In the recent years there has been interest in the behavior of the differences $\mathsf{s}(n+t)-\mathsf{s}(n)$, where $t \geq 0$ is an integer. In particular, Spiegelhofer and Wallner showed that for $t$ whose binary expansion contains sufficiently many blocks of $\mathtt{1}$s the inequality $\mathsf{s}(n+t) -\mathsf{s}(n) \geq 0$ holds for $n$ belonging to a set of asymptotic density $>1/2$, partially answering a question by Cusick. Furthermore, for such $t$ the values $\mathsf{s}(n+t) - \mathsf{s}(n)$ are approximately normally distributed. In this paper we consider a natural generalization to the family of block-counting functions $N^w$, giving the number of occurrences of a block of binary digits $w$ in the binary expansion. Our main result show that for any $w$ of length at least $2$ the distribution of the differences $N^w(n+t) - N^w(n)$ is close to a Gaussian when $t$ contains many blocks of $\mathtt{1}$s in its binary expansion. This extends an earlier result by the author and Spiegelhofer for $w=\mathtt{11}$.
format Preprint
id arxiv_https___arxiv_org_abs_2412_15851
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the behavior of binary block-counting functions under addition
Sobolewski, Bartosz
Number Theory
Combinatorics
11A63, 11BO5, 05A16
Let $\mathsf{s}(n)$ denote the sum of binary digits of an integer $n \geq 0$. In the recent years there has been interest in the behavior of the differences $\mathsf{s}(n+t)-\mathsf{s}(n)$, where $t \geq 0$ is an integer. In particular, Spiegelhofer and Wallner showed that for $t$ whose binary expansion contains sufficiently many blocks of $\mathtt{1}$s the inequality $\mathsf{s}(n+t) -\mathsf{s}(n) \geq 0$ holds for $n$ belonging to a set of asymptotic density $>1/2$, partially answering a question by Cusick. Furthermore, for such $t$ the values $\mathsf{s}(n+t) - \mathsf{s}(n)$ are approximately normally distributed. In this paper we consider a natural generalization to the family of block-counting functions $N^w$, giving the number of occurrences of a block of binary digits $w$ in the binary expansion. Our main result show that for any $w$ of length at least $2$ the distribution of the differences $N^w(n+t) - N^w(n)$ is close to a Gaussian when $t$ contains many blocks of $\mathtt{1}$s in its binary expansion. This extends an earlier result by the author and Spiegelhofer for $w=\mathtt{11}$.
title On the behavior of binary block-counting functions under addition
topic Number Theory
Combinatorics
11A63, 11BO5, 05A16
url https://arxiv.org/abs/2412.15851