A128653 - OEIS

%I #8 Sep 20 2024 05:42:24

%S 43,53,59,79,113,151,163,167,197,229,269,313,331,359,367,397,419,421,

%T 449,541,607,617,619,683,719,739,757,857,883,887,907,911,997,1021,

%U 1051,1063,1103,1117,1193,1249,1289,1303,1427,1433,1459,1471,1489,1493,1499

%N Primes occurring in A084704 exactly twice.

%e 43 occurs as the 7th and 10th terms in A084704: (prime(8)+43)/2 = (19+43)/2 = 31 prime and (prime(11)+43)/2 = (31+43)/2 = 37 prime;

%e 53 is 9th and 12th terms in A084704: (prime(10)+53)/2 = (29+53)/2 = 41 prime and (prime(13)+53)/2 = (41+53)/2 = 47 prime.

%Y For primes occurring in A084704 exactly 3 and 4 times see A128654, A128655. Cf. A084704 Smallest prime p > prime(n) such that (p+prime(n))/2 is prime.

%K nonn

%O 1,1

%A _Zak Seidov_, Mar 18 2007