A142025 Primes congruent to 21 mod 31.

83, 269, 331, 641, 827, 1013, 1447, 1571, 2129, 2377, 2687, 2749, 3121, 3307, 3617, 3803, 3989, 4051, 4423, 4547, 4733, 4919, 5167, 5477, 5849, 6221, 6469, 6779, 6841, 7027, 7151, 7213, 7523, 8081, 8329, 8887, 9011, 9631, 9817, 9941, 10313, 10499, 11057, 11119

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, A142005, A142006, A142023.

Programs

Magma

[p: p in PrimesUpTo(12000) | p mod 31 eq 21 ]; // Vincenzo Librandi, Aug 17 2012

Mathematica

Select[Range[21,20000,31],PrimeQ] (* Vladimir Joseph Stephan Orlovsky, Apr 30 2011 *)
Select[Prime[Range[1500]],Mod[#,31]==21&] (* Harvey P. Dale, Aug 20 2024 *)

PARI

is(n)=isprime(n) && n%31==21 \\ Charles R Greathouse IV, Jul 03 2016

Formula

a(n) ~ 30n log n. - Charles R Greathouse IV, Jul 03 2016