
doi: 10.1007/bf02942044
handle: 10355/10838
Let \(\varphi\) and \(\lambda\) be the Euler and Carmichael functions, respectively. In this paper, the authors establish lower and upper bounds for the counting function of the set \(\mathcal A(x) = \{n\leq x\mid \varphi(\lambda(n))=\lambda(\varphi(n))\}\). The main results are the following: Theorem 1. There exist positive constants \(C\) and \(x_0\) such that the following bound holds for all \(x\geq x_0\): \[ \#\mathcal A(x)\geq \exp \left(C \frac{\log x}{\log\log x}\right). \] Theorem 2. The inequality \[ \#\mathcal A(x)\leq \frac{x}{(\log x)^{3/2+o(1)}} \] holds as \(x\to\infty\). They also study the normal order of the function \(\varphi(\lambda(n))/\lambda(\varphi(n))\). Theorem 3: The estimate \[ \frac{\varphi(\lambda(n))}{\lambda(\varphi(n))}=\exp\bigl((1+o(1))(\log\log n)^2\log\log\log n\bigr) \] holds on a set of positive integers \(n\) of asymptotic density one. In particular, one sees that \(\varphi(\lambda(n))\) is much larger than \(\lambda(\varphi(n))\) for almost all positive integers \(n\).
Other results on the distribution of values or the characterization of arithmetic functions, Euler function, Carmichael function, positive integers, composition of Euler function and Carmichael function, normal order, Distribution of integers with specified multiplicative constraints, 510
Other results on the distribution of values or the characterization of arithmetic functions, Euler function, Carmichael function, positive integers, composition of Euler function and Carmichael function, normal order, Distribution of integers with specified multiplicative constraints, 510
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