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
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