  We provide an asymptotic estimate for certain sums over k-free integers with
small prime factors. These sums depend upon a complex parameter \alpha and
involve a smooth cut-off f. They are a variation of several classical
number-theoretical sums. One term in the asymptotics is an integral operator
whose kernel is the \alpha-convolution of the Dickman-de Bruijn distribution,
and the other term is explicitly estimated. The trade-off between the value of
\alpha and the regularity of f is discussed. This work generalizes the results
of tow previous papers by the author and Ya.G. Sinai, where k=2 and \alpha=1.
