OFFSET
1,1
LINKS
Ray Chandler, Table of n, a(n) for n = 1..13
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