A153769 Numbers n such that 8n-9 is not prime.

0, 1, 3, 6, 8, 9, 12, 13, 15, 16, 18, 19, 21, 23, 24, 27, 28, 30, 32, 33, 36, 37, 38, 39, 41, 42, 43, 44, 45, 48, 50, 51, 52, 53, 54, 57, 58, 60, 63, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 78, 79, 81, 83, 84, 85, 86, 87, 88, 89, 90

Offset: 1

Author

Vincenzo Librandi, Jan 01 2009

Keywords

• nonn
• easy

Examples

			Distribution of the terms > a(2) in the following triangular array:
*;
3,*;
*,*,*;
*,*,9,*;
*,8,*,*,*;
6,*,*,*,19,*;
*,*,*,18,*,*,*;
*,*,16,*,*,*,33,*;
*,13,*,*,*,32,*,*,*;
9,*,*,*,30,*,*,*,51,*;
*,*,*,27,*,*,*,50,*,*,*;
*,*,23,*,*,*,48,*,*,*,73,*;
*,18,*,*,*,45,*,*,*,72,*,*,*;
12,*,*,*,41,*,*,*,70,*,*,*,99,*; etc.
where * marks the non-integer values of (2*h*k + k + h + 5)/4 with h >= k >= 1. - _Vincenzo Librandi_, Jan 19 2013
		

Links

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

Crossrefs

Cf. A153766.

Programs

Magma

[n: n in [0..100]| not IsPrime(8*n-9)]; // Vincenzo Librandi, Jul 31 2012

Mathematica

lst={};Do[If[!PrimeQ[8*n-9],AppendTo[lst,n]],{n,0, 500}];lst (* Vincenzo Librandi, Jul 31 2012 *)
Select[Range[0,100],!PrimeQ[8#-9]&] (* Harvey P. Dale, Jun 08 2015 *)