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

1,1

Links

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

Example

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

Mathematica

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

Prog

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

Crossrefs

A102342.

Sequence in context: A138671 A286693 A032724 * A370856 A216565 A285938

Adjacent sequences: A153305 A153306 A153307 * A153309 A153310 A153311

Keyword

nonn,easy

Author

Vincenzo Librandi, Dec 23 2008

Status

approved