OFFSET
1,1
COMMENTS
Subsequence of A053176. - Michel Marcus, Jan 12 2015
The sequence is infinite. Among others it contains all the primes of the form 15m+/-2. - Emmanuel Vantieghem, Sep 19 2016
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..10000
MAPLE
select(p->isprime(p) and not isprime(2*p+1) and not isprime(2*p-1), [$1..530]); # Muniru A Asiru, Oct 16 2018
MATHEMATICA
lst={}; Do[p=Prime[n]; If[ !PrimeQ[2*p-1]&&!PrimeQ[2*p+1], AppendTo[lst, p]], {n, 6!}]; lst (* Vladimir Joseph Stephan Orlovsky, May 12 2010 *)
Select[Prime[Range[500]], ! PrimeQ[2*# - 1] && ! PrimeQ[2*# + 1] &] (* G. C. Greubel, Oct 15 2018 *)
PROG
(PARI) listp(nn) = {forprime(p=2, nn, if (!isprime(2*p-1) && !isprime(2*p+1), print1(p, ", ")); ); } \\ Michel Marcus, Jan 12 2015
(Magma) [p: p in PrimesUpTo(600) | not IsPrime(2*p+1) and not IsPrime(2*p-1)]; // Vincenzo Librandi, Jan 20 2015
(GAP) Filtered([1..530], p->IsPrime(p) and not IsPrime(2*p+1) and not IsPrime(2*p-1)); # Muniru A Asiru, Oct 16 2018
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Mar 25 2002
STATUS
approved