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A115986
Primes p such that the average of p and nextprime(p) is a power of 3.
4
7, 79, 387420479, 3486784393, 7509466514979724803946715958257527, 147808829414345923316083210206383297581
OFFSET
1,1
LINKS
EXAMPLE
Nextprime(387420479) = 387420499 and (387420479 + 387420499)/2 = 387420489 = 3^18.
PROG
(PARI) lista(nn) = for(k=1, nn, if(precprime(3^k-1)+nextprime(3^k+1)==2*3^k, print1(precprime(3^k-1), ", "))); \\ Jinyuan Wang, Feb 26 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Resta, Feb 10 2006
STATUS
approved