A155722 Numbers k such that 2*k + 9 is prime.

1, 2, 4, 5, 7, 10, 11, 14, 16, 17, 19, 22, 25, 26, 29, 31, 32, 35, 37, 40, 44, 46, 47, 49, 50, 52, 59, 61, 64, 65, 70, 71, 74, 77, 79, 82, 85, 86, 91, 92, 94, 95, 101, 107, 109, 110, 112, 115, 116, 121, 124, 127, 130, 131, 134, 136, 137, 142, 149, 151, 152, 154, 161, 164

Offset: 1

Author

Vincenzo Librandi, Jan 25 2009

Keywords

• nonn
• easy

Comments

Subsequence of A001651; A011655(a(n)) = 1. - Reinhard Zumkeller, Jul 09 2010

One less than the associated entry in A105760, two less than in A089038, three less than in A067076. - R. J. Mathar, Jan 05 2011

Links

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

Crossrefs

Cf. A155723, A155724.

Numbers h such that 2*h + k is prime: A005097 (k=1), A067076 (k=3), A089038 (k=5), A105760 (k=7), this seq (k=9), A101448 (k=11), A153081 (k=13), A089559 (k=15), A173059 (k=17), A153143 (k=19).

Programs

GAP

Filtered([0..200], k-> IsPrime(2*k+9)); # G. C. Greubel, May 21 2019

Magma

[n: n in [0..200] | IsPrime(2*n+9)]; // Vincenzo Librandi, Sep 24 2012

Mathematica

(Prime[Range[5, 100]] - 9)/2 (* Vladimir Joseph Stephan Orlovsky, Feb 08 2010 *)
Select[Range[0, 200], PrimeQ[2 # + 9]&] (* Vincenzo Librandi, Sep 24 2012 *)

PARI

is(n)=isprime(2*n+9) \\ Charles R Greathouse IV, Jul 12 2016

Sage

[n for n in (0..200) if is_prime(2*n+9) ] # G. C. Greubel, May 21 2019

Extensions

Edited by N. J. A. Sloane, Jun 23 2010

Definition clarified by Zak Seidov, Jul 11 2014