A023237 Primes p such that 10*p + 1 is also prime.

3, 7, 13, 19, 31, 43, 97, 103, 109, 151, 157, 181, 193, 211, 241, 271, 337, 349, 367, 409, 421, 439, 487, 523, 547, 571, 601, 613, 631, 691, 733, 769, 811, 823, 829, 883, 937, 1009, 1021, 1033, 1039, 1063, 1069, 1117, 1201, 1249, 1279, 1291, 1459, 1483, 1489

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• easy

Comments

Primes which with a 1 appended stay prime.

Corresponding values of 10n + 1 in A055781. - Jaroslav Krizek, Jul 14 2010

Subsequence of A024912. - Michel Marcus, May 21 2014

Links

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

Crossrefs

Cf. A024912, A055781, A105435, A005384 (2*p + 1), A158017 (10*p - 1).

Programs

Magma

[n: n in [0..1000] | IsPrime(n) and IsPrime(10*n+1)]; // Vincenzo Librandi, Nov 20 2010

Magma

[p: p in PrimesUpTo(1100)| IsPrime(10*p+1)]; // Vincenzo Librandi, May 21 2014

Maple

with(numtheory); for i from 1 to 500 do if isprime(10*ithprime(i)+1) then printf(`%d,`, ithprime(i)) fi: od: # James Sellers, Apr 09 2005

Mathematica

Select[Prime[Range[ 240]], PrimeQ[FromDigits[Join[IntegerDigits[ # ], {1}]]] &] (* Robert G. Wilson v, Apr 09 2005 *)
Select[Prime[Range[900]], PrimeQ[10 # + 1] &] (* Vincenzo Librandi, May 21 2014 *)

Extensions

Edited by N. J. A. Sloane at the suggestion of M. F. Hasler, Aug 24 2007