A141882 Primes congruent to 7 mod 20.

7, 47, 67, 107, 127, 167, 227, 307, 347, 367, 467, 487, 547, 587, 607, 647, 727, 787, 827, 887, 907, 947, 967, 1087, 1187, 1307, 1327, 1367, 1427, 1447, 1487, 1567, 1607, 1627, 1667, 1747, 1787, 1847, 1867, 1907, 1987, 2027, 2087, 2207, 2267, 2287, 2347, 2447

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, A141883.

Programs

Magma

[p: p in PrimesUpTo(3000) | p mod 20 eq 7 ]; // Vincenzo Librandi, Aug 16 2012

Mathematica

Select[Range[7,5000,20],PrimeQ[#]&] (* Vladimir Joseph Stephan Orlovsky, Mar 31 2011*)
Select[Prime[Range[400]],Mod[#,20]==7&] (* Harvey P. Dale, Jan 08 2023 *)

PARI

is(n)=isprime(n) && n%20==7 \\ Charles R Greathouse IV, Jul 01 2016