English

Completely multiplicative functions taking values in $\{-1,1\}$

Number Theory 2008-09-11 v1

Abstract

Define {\em the Liouville function for AA}, a subset of the primes PP, by λA(n)=(1)ΩA(n)\lambda_{A}(n) =(-1)^{\Omega_A(n)} where ΩA(n)\Omega_A(n) is the number of prime factors of nn coming from AA counting multiplicity. For the traditional Liouville function, AA is the set of all primes. Denote LA(n):=knλA(n)andRA:=limnLA(n)n.L_A(n):=\sum_{k\leq n}\lambda_A(n)\quad{and}\quad R_A:=\lim_{n\to\infty}\frac{L_A(n)}{n}. We show that for every α[0,1]\alpha\in[0,1] there is an APA\subset P such that RA=αR_A=\alpha. Given certain restrictions on AA, asymptotic estimates for knλA(k)\sum_{k\leq n}\lambda_A(k) are also given. With further restrictions, more can be said. For {\em character--like functions} λp\lambda_p (λp\lambda_p agrees with a Dirichlet character χ\chi when χ(n)0\chi(n)\neq 0) exact values and asymptotics are given; in particular knλp(k)logn.\quad\sum_{k\leq n}\lambda_p(k)\ll \log n. Within the course of discussion, the ratio ϕ(n)/σ(n)\phi(n)/\sigma(n) is considered.

Keywords

Cite

@article{arxiv.0809.1691,
  title  = {Completely multiplicative functions taking values in $\{-1,1\}$},
  author = {Peter Borwein and Stephen K. K. Choi and Michael Coons},
  journal= {arXiv preprint arXiv:0809.1691},
  year   = {2008}
}
R2 v1 2026-06-21T11:18:37.451Z