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A153380 Numbers n such that 10*n+9 is not prime. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified March 25 11:34 EDT 2017. Contains 284076 sequences.