It has been proved that the only solutions to the Diophantine Equation

are , 4, 5, 7, and 15 (Beeler

**References**

Beeler, M.; Gosper, R. W.; and Schroeppel, R. *HAKMEM.* Cambridge, MA: MIT Artificial Intelligence Laboratory, Memo AIM-239, Feb. 1972.

© 1996-9

1999-05-25