A141884 Primes congruent to 11 mod 20.

11, 31, 71, 131, 151, 191, 211, 251, 271, 311, 331, 431, 491, 571, 631, 691, 751, 811, 911, 971, 991, 1031, 1051, 1091, 1151, 1171, 1231, 1291, 1451, 1471, 1511, 1531, 1571, 1811, 1831, 1871, 1931, 1951, 2011, 2111, 2131, 2251, 2311, 2351, 2371, 2411, 2531, 2551

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, A105854, A141881, A141882, A141883.

Programs

Magma

[p: p in PrimesUpTo(3000) | p mod 20 eq 11 ]; // Vincenzo Librandi, Aug 16 2012

Mathematica

Select[Range[11,5000,20],PrimeQ[#]&] (* Vladimir Joseph Stephan Orlovsky, Mar 31 2011*)
Select[Prime[Range[400]],Mod[#,20]==11&] (* Harvey P. Dale, Aug 10 2021 *)

PARI

is(n)=isprime(n) && n%20==11 \\ Charles R Greathouse IV, Jul 03 2016

Formula

a(n) ~ 8n log n. - Charles R Greathouse IV, Jul 03 2016