On the difficulty of finding reliable witnesses (with Red Alford and Carl Pomerance)
Algorithmic Number Theory, (ANTS-I proceedings, eds L.M. Adleman and M.D. Huang), Lectures Notes in Computer Sci.,
877 (1994), 1-16.
We show that for any finite set of primes there are infinitely many Carmichael numbers that are also strong pseudoprimes with respect to the base given by each of the finite set of primes