A153261 Primes p such that 3*p-2 is not prime.

2, 17, 19, 29, 31, 41, 59, 73, 79, 83, 89, 97, 101, 107, 109, 131, 139, 149, 151, 157, 173, 179, 197, 199, 223, 227, 229, 233, 239, 241, 269, 281, 283, 311, 317, 349, 353, 359, 367, 379, 383, 389, 397, 409, 419, 421, 439, 449, 457, 463, 479, 499, 503, 509, 521

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Dec 22 2008

Keywords

• nonn

Comments

3*2-2=4 not prime, 17*3-2=49 not prime,... 3*3-2=7 is prime and not in this sequence.

Crossrefs

Cf. A153184, A088878

Cf. A153238 [From Vincenzo Librandi, Jan 01 2009]

Programs

Mathematica

lst={};Do[p=Prime[n];If[ !PrimeQ[3*p-2],AppendTo[lst,p]],{n,6!}];lst

Extensions

Minor edits by N. J. A. Sloane, Jul 08 2010