Can two neighbouring primes average to a prime
Question
Take two primes with no prime strictly between them. Is it possible for to be prime?
Short answer
No. For the mean is not an integer. Otherwise the mean is an integer lying strictly between and , and since are consecutive primes, no integer in that gap is prime.
Adapted from Crack, Heard on the Street, Q1.68, p.21; question and answer rewritten by SelfMadeQuant.com.
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