A169647 Primes p such that (p-2)/3 is not a prime number.

2, 3, 5, 7, 13, 19, 29, 31, 37, 43, 47, 61, 67, 73, 79, 83, 97, 101, 103, 107, 109, 127, 137, 139, 149, 151, 157, 163, 167, 173, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 241, 257, 263, 271, 277, 281, 283, 307, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379

Offset

1,1

Comments

The old definition was "Start with the list of primes; accept 2 but remove the list of primes S(2), defined in the comments; accept the next prime (3) but remove the list of primes S(3); repeat".

If p is a prime, S(p) denotes the list of primes {3p+2, 3(3p+2)+2, 3(3(3p+2)+2)+2, ...}, stopping as soon as we reach the first composite number. Thus S(2) = {}, S(3) = {11}, S(5) = {17, 53}, S(7) = {23, 71}, etc.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Mathematica

Select[Prime[Range[80]], !PrimeQ[(#-2)/3]&] (* Harvey P. Dale, Mar 08 2012 *)

Crossrefs

Sequence in context: A153800 A362777 A147791 * A072467 A062326 A198273

Adjacent sequences: A169644 A169645 A169646 * A169648 A169649 A169650

Keyword

nonn,easy

Author

N. J. A. Sloane, Apr 05 2010, based on an email message from Vincenzo Librandi.

Extensions

Checked by Dan Drake, Jun 17 2010

New definition from Jon E. Schoenfield, Jun 18 2010

Status

approved