A153086 Numbers n such that 4*n+7 is not prime

2, 5, 7, 8, 11, 12, 14, 17, 20, 21, 22, 23, 26, 27, 28, 29, 32, 34, 35, 37, 38, 41, 42, 44, 45, 47, 49, 50, 52, 53, 56, 57, 59, 60, 62, 63, 65, 67, 68, 70, 71, 72, 73, 74, 77, 78, 79, 80, 82, 83, 84, 86, 87, 89, 91, 92, 95, 96, 97, 98, 99, 100, 101, 102, 104, 105, 107

Offset

1,1

Links

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

Example

*;
2, *;
*, 7, *;
5, *, 14, *;
*, 12, *, 23, *;
8, *, 21, *, 34, *;
*, 17, *, 32, *, 47, *; etc.
where * marks the non-integer values of (2*n*k + k + n - 3)/2 with n >= k >= 1. - Vincenzo Librandi, Nov 21 2012

Mathematica

Select[Range[200], !PrimeQ[4# + 7] &] (* Vincenzo Librandi, Nov 21 2012 *)

Prog

(Magma) [n: n in [1..120] | not IsPrime(4*n + 7)]; // Vincenzo Librandi, Nov 21 2012

Crossrefs

Cf. A089986, A153053.

Sequence in context: A299232 A153083 A140592 * A032784 A277266 A047268

Adjacent sequences: A153083 A153084 A153085 * A153087 A153088 A153089

Keyword

nonn,easy

Author

Vincenzo Librandi, Dec 18 2008

Status

approved