High Quality Content by WIKIPEDIA articles! Wall-Sun-Sun primes are named after D. D. Wall, Zhi Hong Sun and Zhi Wei Sun; Z. H. Sun and Z. W. Sun showed in 1992 that if the first case of Fermat's last theorem was false for a certain prime p, then p would have to be a Wall-Sun-Sun prime. As a result, prior to Andrew Wiles' proof of Fermat's last theorem, the search for Wall-Sun-Sun primes was also the search for a counterexample to this centuries-old conjecture. No Wall-Sun-Sun primes are known as of March 2010. In 2007, Richard J. McIntosh and Eric L. Roettger showed that if any exist, they must be 2 × 1014. It has been conjectured that there are infinitely many Wall-Sun-Sun primes.