A153769 - OEIS

A153769

Numbers n such that 8n-9 is not prime.

0, 1, 3, 6, 8, 9, 12, 13, 15, 16, 18, 19, 21, 23, 24, 27, 28, 30, 32, 33, 36, 37, 38, 39, 41, 42, 43, 44, 45, 48, 50, 51, 52, 53, 54, 57, 58, 60, 63, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 78, 79, 81, 83, 84, 85, 86, 87, 88, 89, 90

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OFFSET

1,3

LINKS

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

EXAMPLE

Distribution of the terms > a(2) in the following triangular array:

3,*;

*,*,*;

*,*,9,*;

*,8,*,*,*;

6,*,*,*,19,*;

*,*,*,18,*,*,*;

*,*,16,*,*,*,33,*;

*,13,*,*,*,32,*,*,*;

9,*,*,*,30,*,*,*,51,*;

*,*,*,27,*,*,*,50,*,*,*;

*,*,23,*,*,*,48,*,*,*,73,*;

*,18,*,*,*,45,*,*,*,72,*,*,*;

12,*,*,*,41,*,*,*,70,*,*,*,99,*; etc.

where * marks the non-integer values of (2*h*k + k + h + 5)/4 with h >= k >= 1. - Vincenzo Librandi, Jan 19 2013

MATHEMATICA

lst={}; Do[If[!PrimeQ[8*n-9], AppendTo[lst, n]], {n, 0, 500}]; lst (* Vincenzo Librandi, Jul 31 2012 *)

Select[Range[0, 100], !PrimeQ[8#-9]&] (* Harvey P. Dale, Jun 08 2015 *)

PROG

(Magma) [n: n in [0..100]| not IsPrime(8*n-9)]; // Vincenzo Librandi, Jul 31 2012

CROSSREFS

Cf. A153766.

Sequence in context: A084020 A167195 A032489 * A275608 A363758 A155723

Adjacent sequences: A153766 A153767 A153768 * A153770 A153771 A153772

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Jan 01 2009

STATUS

approved