OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
EXAMPLE
For prime p = 199, 6*p^2+1 = 237607 is prime.
MATHEMATICA
Select[Prime[Range[500]], PrimeQ[(6 #^2 + 1)]&] (* Vincenzo Librandi, Apr 14 2013 *)
PROG
(Magma) [ p: p in PrimesUpTo(3300) | IsPrime(6*p^2+1) ];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Klaus Brockhaus, Jan 01 2009
STATUS
approved