Carmichael Numbers with a Specified Number of Prime Factors
Daniel Larsen, Thomas Wright
TL;DR
This work proves that for all sufficiently large $R$ there exists a Carmichael number with exactly $R$ prime factors, extending the AGP framework with an unconditional construction. By developing equidistribution in carefully crafted prime sets $\mathcal{P}$ built from moduli $L$ and $k$, and leveraging Davenport-type bounds and combinatorial lemmas, the authors show large classes of products yield Carmichael numbers with prescribed $\omega(n)$. They handle both even and odd $\omega(n)$ counts, notably fixing a small prime factor to realize odd counts, and then use a covering argument across scales to conclude that every sufficiently large $R$ occurs. The results provide an unconditional route toward realizing exact prime-factor counts in Carmichael numbers, contributing a significant strengthening of the landscape around Korselt-type constructions and equidistribution methods.
Abstract
For every sufficiently large integer $R$, there exists a Carmichael number with exactly $R$ prime factors.
