A153380 Numbers n such that 10*n+9 is not prime.

0, 3, 4, 6, 9, 11, 12, 15, 16, 18, 20, 21, 24, 25, 27, 28, 29, 30, 31, 32, 33, 36, 39, 42, 45, 46, 48, 51, 52, 53, 54, 55, 57, 58, 60, 62, 63, 64, 66, 67, 68, 69, 72, 74, 75, 77, 78, 79, 81, 84, 86, 87, 88, 89, 90, 93, 94, 95, 96, 97, 98, 99, 102

Offset

1,2

Links

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

Example

Triangle begins:
0;
*,*;
*,*,4;
*,*,*,*;
*,*,*,*,*;
3,*,*,*,*,16;
*,*,*,*,*,*,*;
*,*,11,*,*,*,*,28;
*,*,*,*,20,*,*,*,*;
*,*,*,*,*,*,*,*,*,*;
6,*,*,*,*,29,*,*,*,*,52;
where * marks the non-integer values of (2*h*k + k + h - 4)/5 with h >= k >= 1. - Vincenzo Librandi, Jan 13 2013

Mathematica

Select[Range[0, 200], !PrimeQ[10 # + 9] &] (* Vincenzo Librandi, Jan 13 2013 *)

Prog

(Magma) [n: n in [0..150] | not IsPrime(10*n+9)]; // Vincenzo Librandi, Jan 13 2013

Crossrefs

Cf. A102700.

Sequence in context: A087805 A213040 A173318 * A268273 A034027 A184795

Adjacent sequences: A153377 A153378 A153379 * A153381 A153382 A153383

Keyword

nonn,easy

Author

Vincenzo Librandi, Dec 25 2008

Extensions

0 added by Arkadiusz Wesolowski, Aug 03 2011

Status

approved