English

Increasing-decreasing patterns in the iteration of an arithmetic function

Number Theory 2025-03-03 v4

Abstract

Let Ω\Omega be a set of positive integers and let f:ΩΩf:\Omega \rightarrow \Omega be an arithmetic function. Let V=(vi)i=1nV = (v_i)_{i=1}^n be a finite sequence of positive integers. An integer mΩm \in \Omega has \textit{increasing-decreasing pattern} VV with respect to ff if, for all odd integers i{1,,n}i \in \{1,\ldots, n\}, fv1++vi1(m)<fv1++vi1+1(m)<<fv1++vi1+vi(m) f^{v_1+ \cdots + v_{i-1}}(m) < f^{v_1+ \cdots + v_{i-1}+1}(m) < \cdots < f^{v_1+ \cdots + v_{i-1}+v_{i}}(m) and, for all even integers i{2,,n}i \in \{2,\ldots, n\}, fv1++vi1(m)>fv1++vi1+1(m)>>fv1++vi1+vi(m). f^{v_1+ \cdots + v_{i-1}}(m) > f^{v_1+ \cdots +v_{i-1}+1}(m) > \cdots > f^{v_1+ \cdots +v_{i-1}+v_i}(m). The arithmetic function ff is \textit{wildly increasing-decreasing} if, for every finite sequence VV of positive integers, there exists an integer mΩm \in \Omega such that mm has increasing-decreasing pattern VV with respect to ff. This paper gives a proof that the Syracuse function is wildly increasing-decreasing.

Cite

@article{arxiv.2208.02242,
  title  = {Increasing-decreasing patterns in the iteration of an arithmetic function},
  author = {Melvyn B. Nathanson},
  journal= {arXiv preprint arXiv:2208.02242},
  year   = {2025}
}

Comments

14 pages, improved and expanded

R2 v1 2026-06-25T01:27:25.465Z