Nicolaas Govert de Bruijn, the enchanter of friable integers
  N.G. de Bruijn carried out fundamental work on integers having only small prime factors and the Dickman-de Bruijn function that arises on computing the density of those integers. In this he used his earlier work on linear functionals and differential-difference equations. We review the relevant work and also some later improvements by others. 
Pieter Moree
math.NT math.HO