The image of Carmichael's $\lambda$-function

Abstract

We show that the counting function of the set of values of Carmichael’s $\lambda$-function is $x∕{\left(logx\right)}^{\eta +o\left(1\right)}$, where $\eta =1-\left(1+loglog2\right)∕\left(log2\right)=0.08607\dots$.