Problems & Puzzles:
JM Bergot poses the following nice puzzle:
four consecutive primes,a<b<c<d such that b^c=a(mod
Here are two solutions:
Are these rare solutions?
Wow!!!... contributions came from Farid Lian, Farideh Firoozbakht,
Seiji Tomita, Jacques Tramu, Torbjörn Alm, Jim Howell, Fred Schneider,
Jan van Delden, Luca Poletti & J. K. Andersen.
All of them found only two more solutions:
61^67=59 (mod 71)
77617^77621=77611 (mod 77641)
Fred & Andersen argued that there must be infinite solutions.