• Compositions with the Euler and Carmichael Functions 

    Banks, William David, 1964-; Luca, Florian; Saidak, Filip; Stănică, Pantelimon (Springer Verlag, 2005)
    Let ' and _ be the Euler and Carmichael functions, respectively. In this paper, we establish lower and upper bounds for the number of positive integers n ≤ x such that '(_(n)) = _('(n)). We also study the normal order of ...