English

Some normal numbers generated by arithmetic functions

Number Theory 2019-08-15 v1

Abstract

Let g2g \geq 2. A real number is said to be g-normal if its base g expansion contains every finite sequence of digits with the expected limiting frequency. Let \phi denote Euler's totient function, let \sigma be the sum-of-divisors function, and let \lambda be Carmichael's lambda-function. We show that if f is any function formed by composing \phi, \sigma, or \lambda, then the number 0.f(1)f(2)f(3) 0. f(1) f(2) f(3) \dots obtained by concatenating the base g digits of successive f-values is g-normal. We also prove the same result if the inputs 1, 2, 3, \dots are replaced with the primes 2, 3, 5, \dots. The proof is an adaptation of a method introduced by Copeland and Erdos in 1946 to prove the 10-normality of 0.235711131719\ldots.

Keywords

Cite

@article{arxiv.1309.7386,
  title  = {Some normal numbers generated by arithmetic functions},
  author = {Paul Pollack and Joseph Vandehey},
  journal= {arXiv preprint arXiv:1309.7386},
  year   = {2019}
}
R2 v1 2026-06-22T01:35:51.860Z