A153184 Numbers n such that 3*n-2 is not prime.

1, 2, 4, 6, 8, 9, 10, 12, 14, 16, 17, 18, 19, 20, 22, 24, 26, 28, 29, 30, 31, 32, 34, 36, 38, 39, 40, 41, 42, 44, 45, 46, 48, 49, 50, 52, 54, 56, 57, 58, 59, 60, 62, 63, 64, 66, 68, 69, 70, 72, 73, 74, 76, 78, 79, 80, 82, 83, 84, 85, 86, 87, 88, 89, 90, 92, 94, 96, 97, 98, 99, 100

Offset

1,2

Comments

One more than the associated value in A153309. - R. J. Mathar, Jan 05 2011

Links

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

Formula

a(n) ~ n. - Charles R Greathouse IV, Oct 26 2015

Example

Distribution of the odd terms > a(1) in the following triangular array:
*;
*,9;
*,*,17;
*,*,*,*;
*,19,*,*,41;
*,*,31,*,*,57;
*,*,*,*,*,*,*;
*,29,*,*,63,*,*,97;
*,*,45,*,*,83,*,*,121;
*,*, *,*,*,*, *,*, *, *;
*,39,*,*,85,*,*,131,*,*,177;
*,*,59,*,*,109,*,*,159,*,*,209; etc.
where * marks the non-integer values of (4*h*k + 2*k + 2*h + 3)/3 with h >= k >= 1. - Vincenzo Librandi, Jan 17 2013

Mathematica

lst={}; Do[If[ !PrimeQ[3*n-2], AppendTo[lst, n]], {n, 5!}]; lst (* Vladimir Joseph Stephan Orlovsky, Dec 22 2008 *)
Select[Range[0, 100], !PrimeQ[3 # - 2] &] (* Vincenzo Librandi, Jan 12 2013 *)

Prog

(Magma) [n: n in [0..120] | not IsPrime(3*n - 2)]; // Vincenzo Librandi, Jan 12 2013
(PARI) is(n)=!isprime(3*n-2) \\ Charles R Greathouse IV, Oct 26 2015

Crossrefs

Cf. A153183, A088878.

Sequence in context: A285517 A003254 A247875 * A047412 A282760 A355529

Adjacent sequences: A153181 A153182 A153183 * A153185 A153186 A153187

Keyword

nonn,easy

Author

Vincenzo Librandi, Dec 20 2008

Extensions

Erroneous comment deleted by N. J. A. Sloane, Jun 23 2010

Status

approved