A Wilson prime is a prime satisfying W(p) congruent 0 (mod p), where W(p) is the Wilson quotient, or equivalently, (p - 1)! congruent -1 (mod p^2). The first few Wilson primes are 5, 13, and 563 (OEIS A007540). Crandall et al. (1997) showed there are no others less than 5×10^8, a limit that has subsequently been increased to 2×10^13 .

Brown numbers | Wilson quotient | Wilson's theorem