Published online by Cambridge University Press: 18 January 2021
Let G be a finite group and $\chi $ be a character of G. The codegree of
$\chi $ is
${{\operatorname{codeg}}} (\chi ) ={|G: \ker \chi |}/{\chi (1)}$. We write
$\pi (G)$ for the set of prime divisors of
$|G|$,
$\pi ({{\operatorname{codeg}}} (\chi ))$ for the set of prime divisors of
${{\operatorname{codeg}}} (\chi )$ and
$\sigma ({{\operatorname{codeg}}} (G))= \max \{|\pi ({{\operatorname{codeg}}} (\chi ))| : \chi \in {\textrm {Irr}}(G)\}$. We show that
$|\pi (G)| \leq ({23}/{3}) \sigma ({{\operatorname{codeg}}} (G))$. This improves the main result of Yang and Qian [‘The analog of Huppert’s conjecture on character codegrees’, J. Algebra 478 (2017), 215–219].
This work was partially supported by the NSF of China (No. 11671063) and a grant from the Simons Foundation (No. 499532).