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On the distribution of the Cantor-integers

Number Theory 2024-09-09 v3

Abstract

For any positive integer p3p\geq 3, let AA be a proper subset of {0,1,,p1}\{0,1,\ldots, p-1\} with A=s2\sharp A=s\geq 2. Suppose h:{0,1,,s1}Ah: \{0,1,\ldots,s-1\}\to A is a one-to-one map which is strictly increasing with A={h(0),h(1),,h(s1)}A=\{h(0),h(1),\ldots,h(s-1)\}. We focus on so-called Cantor-integers {an}n1\{a_n\}_{n\geq 1}, which consist of these positive integers nn such that all the digits in the pp-ary expansion of nn belong to AA. Let C={n1εnpn:εnA for any positive integer n}\mathfrak{C}=\left\{\sum\limits_{n\geq 1}\frac{\varepsilon_n}{p^n}: \varepsilon_n\in A \text{ for any positive integer } n\right\} be the appropriate Cantor set, and denote the classic self-similar measure supported on C\mathfrak{C} by μC\mu_{\mathfrak{C}}. Now that nlogspn^{\log_s p} is the growth order of ana_n and {annlogsp: n1}\left\{\frac{a_n}{n^{\log_s p}}:~n\geq 1\right\}' is precisely the set {x(μC([0,x]))logsp:xC[h(1)p,1]}\left\{\frac{x}{(\mu_{\mathfrak{C}}([0,x]))^{\log_s p}}: x\in\mathfrak{C}\cap[\frac{h(1)}{p},1]\right\}, where EE' is the set of limit points of EE, we show that {annlogsp: n1}\left\{\frac{a_n}{n^{\log_s p}}:~n\geq 1\right\}' is just an interval [m,M][m,M] with m:=inf{annlogsp:n1}m:=\inf\left\{\frac{a_n}{n^{\log_s p}}:n\geq 1\right\} and M:=sup{annlogsp:n1}M:=\sup\left\{\frac{a_n}{n^{\log_s p}}:n\geq 1\right\}. In particular, {x(μC([0,x]))logsp:xC\{0}}=[m,M]\left\{\frac{x}{(\mu_{\mathfrak{C}}([0,x]))^{\log_s p}}: x\in\mathfrak{C}\backslash\{0\}\right\}=[m,M] if 0A0\in A, and m=q(s1)+rp1,M=q(p1)+prp1m=\frac{q(s-1)+r}{p-1}, M=\frac{q(p-1)+pr}{p-1} if the set AA consists of all the integers in {0,1,,p1}\{0,1,\ldots, p-1\} which have the same remainder r{0,1,,q1}r\in\{0,1,\ldots,q-1\} modulus qq for some positive integer q2q \geq 2 (i.e. h(x)=qx+rh(x)=qx+r). We further show that the sequence {annlogsp}n1\left\{\frac{a_n}{n^{\log_s p}}\right\}_{n\geq 1} is not uniformly distributed modulo 1, and it does not have the cumulative distribution function, but has the logarithmic distribution function (give by a specific Lebesgue integral).

Keywords

Cite

@article{arxiv.2209.05119,
  title  = {On the distribution of the Cantor-integers},
  author = {ChunYun Cao and Jie Yu},
  journal= {arXiv preprint arXiv:2209.05119},
  year   = {2024}
}