Not every number is the sum or difference of two prime powers
Authors: Fred Cohen and J. L. Selfridge
Journal: Math. Comp. 29 (1975), 79-81
MSC: Primary 10J15; Secondary 10-04
MathSciNet review: 0376583
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Abstract: Every odd number less than 262144 is the sum or difference of a power of two and a prime. An interesting example is . Using covering congruences, we exhibit a 26-digit odd number which is neither the sum nor difference of a power of two and a prime. The method is then modified to exhibit an arithmetic progression of numbers which are not the sum or difference of two prime powers.