A370156 - OEIS

%I #12 Feb 17 2024 12:33:46

%S 11,41,53,71,113,131,179,251,311,449,491,521,593,599,683,701,719,773,

%T 809,881,941,1049,1061,1103,1151,1229,1301,1319,1373,1439,1499,1511,

%U 1571,1709,1733,1931,2273,2309,2393,2579,2591,2663,2843,2861,2903,3041,3119

%N Primes p such that (p-2)/3 is prime and 3*p+2 is composite.

%e (11-2)/3 is a prime and 3*11+2 isn't.

%t Select[Prime[Range[500]], ! PrimeQ[3 # + 2] && PrimeQ[(# - 2)/3] &]

%o (PARI) isok(p) = if (isprime(p), !isprime(3*p+2) && (((p%3) == 2) && isprime((p-2)/3))); \\ _Michel Marcus_, Feb 17 2024

%Y Cf. A000040, A115058 (supersequence), A023208, A370157.

%K nonn

%O 1,1

%A _Clark Kimberling_, Feb 10 2024