  The numbers e_p(k,n) defined as min(nu_p(S(k,j)j!): j >= n) appear frequently
in algebraic topology. Here S(k,j) is the Stirling number of the second kind,
and nu_p(-) the exponent of p. The author and Sun proved that if L is
sufficiently large, then e_p((p-1)p^L + n -1, n) >= n-1+nu_p([n/p]!). In this
paper, we determine the set of integers n for which equality holds in this
inequality when p=2 and 3. The condition is roughly that, in the base-p
expansion of n, the sum of two consecutive digits must always be less than p.
