References: [ Home | Author index | Key index | Search ]

Sun2000

Z. Sun, "On integers not of the form ± p^a ± q^b," Proc. Amer. Math. Soc., 128:4 (2000) 997--1002.  MR1695111

Abstract: In 1975 F. Cohen and J.L. Selfridge found a 94-digit positive integer which cannot be written as the sum or difference of two prime powers. Following their basic construction and introducing a new method to avoid a bunch of extra congruences, we are able to prove that if

x≡ 47867742232066880047611079 (mod 66483034025018711639862527490) ,

then x is not of the form ± p^a± q^b where p, q are primes and a, b are nonnegative integers.