A165810 Primes p such that 18*p+1 is also a prime.

2, 7, 11, 17, 29, 41, 59, 71, 79, 97, 127, 137, 139, 149, 151, 181, 197, 199, 241, 251, 277, 281, 307, 337, 347, 367, 379, 401, 431, 479, 491, 541, 569, 587, 659, 701, 709, 757, 797, 809, 821, 827, 829, 857, 877, 881, 947, 991, 1021, 1051, 1109, 1117, 1129, 1151, 1229

Offset

1,1

Links

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

Formula

a(n) = (A165811(n)-1)/18.

Example

For p=2, 18*p+1=37. For p=7, 18*p+1=127. For p=11, 18*p+1=199.

Mathematica

Select[Prime[Range[1000]], PrimeQ[18#+1]&]  (* Harvey P. Dale, Mar 06 2011 *)

Crossrefs

Cf. A111094, A153400, A165811.

Sequence in context: A124854 A240878 A109953 * A109417 A045372 A273600

Adjacent sequences: A165807 A165808 A165809 * A165811 A165812 A165813

Keyword

nonn,easy

Author

Vincenzo Librandi, Sep 28 2009

Extensions

Extended by R. J. Mathar, Oct 16 2009

Status

approved