Let {pj } ∞ j=1 denote the set of prime numbers in increasing order, let ΩN ⊂ N denote the set of positive integers with no prime factor larger than pN and let PN denote the probability measure on ΩN which gives to each n ∈ ΩN a probability proportional to 1 n . This measure is in fact the distribution of the random integer IN ∈ ΩN definedare independent random variables and Xp j is distributed as Geom(1 − 1 p j ). We show that log n log N under PN converges weakly to the Dickman distribution. As a corollary, we recover a classical result from multiplicative number theory-Mertens'We show that the two densities coincide on a natural algebra of subsets of N. We also show that they do not agree on the sets of n 1 s -smooth numbers {n ∈ N : p + (n) ≤ n 1 s }, s > 1, where p + (n) denotes the largest prime divisor of n. This last consideration concerns distributions involving the Dickman function. We also consider the sets of n 1 s -rough numbers {n ∈ N : p − (n) ≥ n 1 s }, s > 1, where p − (n) denotes the smallest prime divisor of n. We show that the probabilities of these sets, under the uniform distribution on [N ] = {1, . . . , N } and under the PN -distribution on ΩN , have the same asymptotic decay profile as functions of s, although their rates are necessarily different. This profile involves the Buchstab function. We also prove a new representation for the Buchstab function.