A023218 Primes p such that 5*p + 4 is also prime.

3, 5, 11, 17, 29, 47, 53, 71, 83, 89, 101, 113, 131, 167, 251, 257, 263, 281, 311, 389, 419, 461, 467, 479, 491, 509, 521, 557, 563, 587, 593, 599, 617, 641, 659, 677, 743, 797, 809, 827, 857, 881, 929, 977, 983, 1019, 1061, 1103, 1187, 1217, 1259, 1277, 1289, 1319

Offset

1,1

Comments

Except for the first term, all terms are congruent to 5 (mod 6). - John Cerkan, Sep 07 2016

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..2000

Maple

A023218:=n->`if`(isprime(n) and isprime(5*n+4), n, NULL): seq(A023218(n), n=1..2*10^3); # Wesley Ivan Hurt, Sep 07 2016

Mathematica

lst={}; Do[If[PrimeQ[n]&&PrimeQ[5*n+4], AppendTo[lst, n]], {n, 13^3}]; lst (* Vladimir Joseph Stephan Orlovsky, Sep 08 2008 *)
Select[Prime[Range[300]], PrimeQ[5#+4]&] (* Harvey P. Dale, Dec 31 2013 *)

Prog

(Magma) [n: n in [0..1000] | IsPrime(n) and IsPrime(5*n+4)]; // Vincenzo Librandi, Nov 20 2010

Crossrefs

Subsequence of primes of A024897.

Sequence in context: A208574 A361275 A342230 * A073022 A129694 A147015

Adjacent sequences: A023215 A023216 A023217 * A023219 A023220 A023221

Keyword

nonn,easy

Author

David W. Wilson

Status

approved