A note on the Duffin-Schaeffer conjecture (1304.0488v1)

Abstract: Given a sequence of real numbers ${\psi(n)}{n\in\mathbb{N}}$ with $0\leq \psi(n)<1$, let $W(\psi)$ denote the set of $x\in[0,1]$ for which $|xn-m|<\psi(n)$ for infinitely many coprime pairs $(n,m)\in\mathbb{N}\times\mathbb{Z}$. The purpose of this note is to show that if there exists an $\epsilon>0$ such that $\sum{n\in\mathbb{N}}\psi(n)^{1+\epsilon}\cdot\frac{\varphi(n)}{n}=\infty,$ then the Lebesgue measure of $W(\psi)$ equals 1.