VOOZH about

URL: https://oeis.org/A153400

⇱ A153400 - OEIS

login
A153400
Numbers k such that 18*k+1 is not prime.
3
0, 3, 5, 8, 12, 13, 14, 16, 18, 19, 20, 23, 25, 26, 28, 31, 33, 36, 37, 38, 39, 40, 43, 44, 47, 48, 50, 53, 54, 57, 58, 60, 61, 63, 66, 67, 68, 69, 70, 73, 74, 75, 76, 77, 78, 80, 82, 83, 84, 88, 89, 91, 93, 95, 96, 98, 101, 102, 103, 105, 106, 107, 108, 109, 110
OFFSET
1,2
LINKS
EXAMPLE
Distribution of the positive terms in the following triangular array:
*;
*,*;
*,*,*;
*,*,*,*;
*,3,*,*,*;
*,*,5,*,*,*;
*,*,*,*,*,*,*;
*,*,*,*,*,*,*,16;
*,*,*,*,*,*,*,*,20;
*,*,*,*,*,*,*,*,*,*;
*,*,*,*,14,*,*,*,*,*,*;
etc.
where * marks the noninteger values of (2*h*k + k + h)/9 with h >= k >= 1. - Vincenzo Librandi, Jan 14 2013
MATHEMATICA
Select[Range[0, 200], !PrimeQ[18 # + 1] &] (* Vincenzo Librandi, Jan 14 2013 *)
PROG
(Magma) [n: n in [0..150] | not IsPrime(18*n+1)]; // Vincenzo Librandi, Jan 14 2013
CROSSREFS
Cf. A111094.
Sequence in context: A115888 A143814 A088971 * A289076 A372519 A342779
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Dec 25 2008
EXTENSIONS
0 added by Arkadiusz Wesolowski, Aug 03 2011
STATUS
approved