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Smooth Values of the Iterates of the Euler Phi-Function

Published online by Cambridge University Press:  20 November 2018

Youness Lamzouri*
Affiliation:
Départment de Mathématiques et Statistique, Université de Montréal, CP 6128 succ Centre-Ville, Montréal, QC, H3C 3J7 e-mail: [email protected]
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Abstract

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Let $\phi (n)$ be the Euler phi-function, define ${{\phi }_{0}}\left( n \right)\,=\,n$ and ${{\phi }_{k+1}}\left( n \right)\,=\,\phi \left( {{\phi }_{k}}\left( n \right) \right)$ for all $k\ge 0$. We will determine an asymptotic formula for the set of integers $n$ less than $x$ for which ${{\phi }_{k}}\left( n \right)$ is $y$-smooth, conditionally on a weak form of the Elliott–Halberstam conjecture.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 2007

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