OFFSET
1,1
FORMULA
a(n) ~ 2n log n. - Charles R Greathouse IV, Apr 05 2016
MAPLE
select(isprime, [seq(seq(30*i+k, k = [11, 13, 17, 19]), i=0..100)]); # Robert Israel, Apr 05 2016
MATHEMATICA
Select[Prime[Range[200]], MemberQ[{11, 13, 17, 19}, Mod[#, 30]]&] (* Harvey P. Dale, Aug 23 2017 *)
PROG
(PARI) is(n)=n\10%3==1 && isprime(n) \\ Charles R Greathouse IV, Apr 05 2016
(Magma) [p: p in PrimesUpTo(700) | p mod 30 in {11, 13, 17, 19}]; // Vincenzo Librandi, Jan 04 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
J. M. Bergot, Apr 05 2016
STATUS
approved