A153308 Numbers n such that 10*n+7 is not prime.

2, 5, 7, 8, 11, 14, 17, 18, 20, 21, 23, 24, 26, 28, 29, 32, 35, 37, 38, 40, 41, 42, 43, 44, 47, 49, 50, 51, 52, 53, 56, 59, 62, 63, 65, 66, 68, 69, 70, 71, 73, 74, 76, 77, 80, 81, 83, 84, 86, 89, 91, 92, 95, 98, 100, 101, 102, 103, 104, 105, 106, 107

Offset: 1

Author

Vincenzo Librandi, Dec 23 2008

Keywords

• nonn
• easy

Examples

			Distribution of the terms in the following triangular array:
*;
*,*;
*,*,*;
2,*,*,*;
*,*,7,*,*;
*,*,*,11,*,*;
*,*,*,*,*,*,*;
*,*,*,*,18,*,*,*;
5,*,*,*,*,24,*,*,*;
*,*,14,*,*,*,*,35,*,*;
*,*,*,20,*,*,*,*,43,*,*;etc.
where * marks the non-integer values of (2*h*k + k + h - 3)/5 with h >= k >= 1. - _Vincenzo Librandi_, Jan 17 2013
		

Links

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

Crossrefs

A102342.

Programs

Magma

[n: n in [0..150] | not IsPrime(10*n + 7)]; // Vincenzo Librandi, Jan 12 2013

Mathematica

Select[Range[0, 200], !PrimeQ[10*# + 7]&] (* Vincenzo Librandi, Jan 12 2013 *)