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
Examples
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
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Programs
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Magma
[n: n in [0..120] | not IsPrime(3*n - 2)]; // Vincenzo Librandi, Jan 12 2013
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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 *) -
PARI
is(n)=!isprime(3*n-2) \\ Charles R Greathouse IV, Oct 26 2015
Formula
a(n) ~ n. - Charles R Greathouse IV, Oct 26 2015
Extensions
Erroneous comment deleted by N. J. A. Sloane, Jun 23 2010
Comments