A155941 Numbers n such that 16*n+1 is not prime.

0, 2, 3, 4, 5, 8, 9, 10, 11, 13, 14, 17, 18, 19, 20, 23, 24, 26, 29, 30, 31, 32, 33, 34, 35, 38, 39, 41, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 56, 57, 59, 60, 62, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 77, 79, 80, 82, 83, 84, 86, 87, 89, 90, 91, 92, 94, 95

Offset: 1

Author

Vincenzo Librandi, Jan 31 2009

Keywords

• nonn
• easy

Examples

			Distribution of a(n)>0 in the following triangular array:
*;
*,*;
*,*,3;
*,*,*,5;
2,*,*,*,*;
*,4,*,*,*,*;
*,*,*,*,*,*,14;
*,*,*,*,*,*,*,18;
*,*,*,*,13,*,*,*,*;
*,*,*,*,*,17,*,*,*,*;
*,*,10,*,*,*,*,*,*,*,33;
*,*,*,14,*,*,*,*,*,*,*,39;
5,*,*,*,*,*,*,*,32,*,*,*,*; etc.
where * marks the non-integer values of (2*h*k + k + h)/8 with h >= k >= 1. - _Vincenzo Librandi_, Jan 15 2013
		

Links

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

Crossrefs

Cf. A094407, A155942, A155943.

Programs

Magma

[n: n in [0..100] |not IsPrime(16*n+1)]; // Vincenzo Librandi, Oct 15 2012

Mathematica

Select[Range[0, 100], !PrimeQ[16 # + 1] &] (* Vincenzo Librandi, Oct 15 2012 *)

Extensions

0 added by Arkadiusz Wesolowski, Aug 03 2011