English

Rational integers as sums of units -- the quadratic case

Number Theory 2026-01-15 v1

Abstract

How many natural numbers below XX can be written as a sum of kk units of the ring of integers of a given number field? We give the asymptotics as XX gets large for quadratic number fields. This solves a problem of Jarden and Narkiewicz from 2007 for quadratic number fields.

Keywords

Cite

@article{arxiv.2601.09517,
  title  = {Rational integers as sums of units -- the quadratic case},
  author = {Christopher Frei and Martin Widmer and Volker Ziegler},
  journal= {arXiv preprint arXiv:2601.09517},
  year   = {2026}
}

Comments

14 pages; comments welcome!