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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 November 18 10:38 EST 2017. Contains 294887 sequences.