On square-free numbers generated from given sets of primes

Abstract

Let $x$ be a positive real number, and $\mathcal{P}\subset [2,\lambda (x)]$ be a set of primes, where $\lambda (x)\in \Omega (x^{\epsilon })$ is a monotone increasing function with $\epsilon \in (0,1)$. We examine $Q_{\mathcal{P}}(x)$, where $Q_{\mathcal{P}}(x)$ is the element count of the set containing those positive square-free integers, which are smaller than-, or equal to $x$, and which are only divisible by the elements of $\mathcal{P}$.