OFFSET
1,2
COMMENTS
After 1, a(n) is congruent to 4 or 9 (mod 10), this means that a(n) is of the form 5k-1. Clearly, each term is not divisible by 3, 7 and 11.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..100
MATHEMATICA
Select[Range[7000000], Union[PrimeQ[2 # +{3, 5, 9, 11, 15, 21}]]=={True}&]
PROG
(Magma) [n: n in [1..11000000] | forall{2*n+k: k in [3, 5, 9, 11, 15, 21] | IsPrime(2*n+k)}];
CROSSREFS
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Mar 13 2013
STATUS
approved