A051647 Primes p such that 210*p + 1 is also prime.

2, 3, 5, 7, 11, 13, 17, 23, 29, 47, 53, 59, 67, 73, 83, 89, 101, 137, 139, 157, 163, 179, 181, 191, 193, 223, 229, 251, 271, 277, 281, 313, 317, 347, 349, 353, 359, 401, 419, 421, 431, 433, 449, 457, 463, 479, 523, 577, 599, 601, 631, 653, 701, 709, 719, 727

Offset

1,1

Comments

Analogous to A005384, Sophie Germain primes.

Links

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

Example

A002110(4)*p + 1 = 210*p + 1 and p are both primes.
11 is in the sequence because 210*11 + 1 = 2311 is also prime.

Mathematica

Select[Prime[Range[200]], PrimeQ[210#+1]&]  (* Harvey P. Dale, Apr 25 2011 *)

Prog

(Magma) [p: p in PrimesUpTo(900) | IsPrime(210*p+1)]; // Vincenzo Librandi, Apr 11 2013

Crossrefs

Cf. A005384, A005385, A007693.

Sequence in context: A181659 A040087 A040065 * A042986 A143390 A038617

Adjacent sequences: A051644 A051645 A051646 * A051648 A051649 A051650

Keyword

nonn,easy

Author

Labos Elemer

Status

approved