A153039 Numbers k such that 2*k-7 is composite.

8, 11, 14, 16, 17, 20, 21, 23, 26, 28, 29, 31, 32, 35, 36, 38, 41, 42, 44, 46, 47, 49, 50, 51, 53, 56, 59, 61, 62, 63, 64, 65, 66, 68, 70, 71, 74, 75, 76, 77, 80, 81, 83, 84, 86, 88, 89, 91, 92, 95, 96, 97, 98, 101, 104, 105, 106, 107, 108, 110, 111, 112

Offset: 1

Author

Vincenzo Librandi, Dec 17 2008

Keywords

• nonn
• easy

Comments

Two more than the associated value in A153043, one more than in A153040.

Links

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

Crossrefs

Complement of A089192, A153040.

Programs

Magma

[n: n in [5..220]| not IsPrime(2*n-7)];

Mathematica

Select[Range[8,200], !PrimeQ[2*#-7]&] (* Vladimir Joseph Stephan Orlovsky, Feb 09 2012 *)

PARI

list(n)=apply(k->(k+7)/2,setminus(vector(n,k,2*k+7), primes(primepi(2*n+7)))) \\ Charles R Greathouse IV, May 14 2012

Extensions

Partially edited by N. J. A. Sloane, Jun 23 2010