A142792 Primes congruent to 31 mod 60.

31, 151, 211, 271, 331, 571, 631, 691, 751, 811, 991, 1051, 1171, 1231, 1291, 1471, 1531, 1831, 1951, 2011, 2131, 2251, 2311, 2371, 2551, 2671, 2731, 2791, 2851, 2971, 3271, 3331, 3391, 3511, 3571, 3631, 3691, 3931, 4051, 4111, 4231, 4591, 4651, 4831, 4951

Offset: 1

Author

N. J. A. Sloane, Jul 11 2008

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000040.

Programs

Magma

[p: p in PrimesUpTo(6000) | p mod 60 eq 31 ]; // Vincenzo Librandi, Sep 04 2012

Mathematica

Select[Prime[Range[1000]],Mod[#,60]==31&]  (* Harvey P. Dale, Mar 14 2011 *)
Select[Prime[Range[800]], MemberQ[{31}, Mod[#, 60]] &] (* Vincenzo Librandi, Sep 04 2012 *)
Select[Range[31,5000,60],PrimeQ] (* Faster because it tests fewer numbers than the programs above *) (* Harvey P. Dale, Nov 13 2013 *)

PARI

is(n)=isprime(n) && n%60==31 \\ Charles R Greathouse IV, Jul 03 2016

Formula

a(n) ~ 16n log n. - Charles R Greathouse IV, Jul 03 2016