A153044 Numbers n such that 2*n-9 is not a prime.

5, 9, 12, 15, 17, 18, 21, 22, 24, 27, 29, 30, 32, 33, 36, 37, 39, 42, 43, 45, 47, 48, 50, 51, 52, 54, 57, 60, 62, 63, 64, 65, 66, 67, 69, 71, 72, 75, 76, 77, 78, 81, 82, 84, 85, 87, 89, 90, 92, 93, 96, 97, 98, 99, 102, 105, 106, 107, 108, 109, 111, 112, 113, 114, 115, 117, 120

Offset: 1

Author

Vincenzo Librandi, Dec 17 2008

Keywords

• nonn
• easy

Comments

One more than the associated entry in A153039. - R. J. Mathar, Jan 05 2011

The terms after a(1) are the values of 2*h*k + k + h + 5, where h and k are positive integers. - Vincenzo Librandi, Jan 19 2013

Links

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

Crossrefs

Cf. A097069, A153039.

Programs

Magma

[n: n in [5..121] | not IsPrime(2*n-9)]; // Bruno Berselli, Mar 05 2011

Mathematica

Select[Range[150],!PrimeQ[2#-9]&]  (* Harvey P. Dale, Mar 05 2011 *)

Extensions

Corrected and extended by N. J. A. Sloane, May 29 2010