OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
EXAMPLE
31 is in the sequence because 2*31+1=63 and 2*31+3=65 are not prime.
MATHEMATICA
Select[Range[10^3], PrimeQ[#]&&!PrimeQ[2 # + 1]&&!PrimeQ[2 # + 3]&]
Select[Prime[Range[200]], NoneTrue[2#+{1, 3}, PrimeQ]&] (* Harvey P. Dale, Sep 19 2021 *)
PROG
(Magma) [p: p in PrimesUpTo(2500)|not IsPrime(2*p+1) and not IsPrime(2*p+3)];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Oct 12 2013
STATUS
approved