English

On the asymptotics of Kempner-Irwin sums

Number Theory 2026-01-16 v4 Classical Analysis and ODEs

Abstract

Let I(b,d,k)I(b,d,k) be the subseries of the harmonic series keeping the integers having exactly kk occurrences of the digit dd in base bb. We prove the existence of an asymptotic expansion to all orders in descending powers of bb, for fixed dd and kk, of I(b,d,k)blog(b)I(b,d,k)-b\log(b). We explicitly give, depending on cases, either four or five terms. The coefficients involve the values of the zeta function at the integers.

Keywords

Cite

@article{arxiv.2404.13763,
  title  = {On the asymptotics of Kempner-Irwin sums},
  author = {Jean-François Burnol},
  journal= {arXiv preprint arXiv:2404.13763},
  year   = {2026}
}

Comments

34 pages. v3 of January 2026 is an English translation of the French original 2404.13763v2 from April 2024. A few changes were made addressing referee remarks from July 2025, and references were updated. Subsequent v4 fixes a few left-over formatting issues and adds a link to the dedicated repository