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A153308 Numbers n such that 10*n+7 is not prime. 1
2, 5, 7, 8, 11, 14, 17, 18, 20, 21, 23, 24, 26, 28, 29, 32, 35, 37, 38, 40, 41, 42, 43, 44, 47, 49, 50, 51, 52, 53, 56, 59, 62, 63, 65, 66, 68, 69, 70, 71, 73, 74, 76, 77, 80, 81, 83, 84, 86, 89, 91, 92, 95, 98, 100, 101, 102, 103, 104, 105, 106, 107 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

Distribution of the terms in the following triangular array:

*;

*,*;

*,*,*;

2,*,*,*;

*,*,7,*,*;

*,*,*,11,*,*;

*,*,*,*,*,*,*;

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

5,*,*,*,*,24,*,*,*;

*,*,14,*,*,*,*,35,*,*;

*,*,*,20,*,*,*,*,43,*,*;etc.

where * marks the non-integer values of (2*h*k + k + h - 3)/5 with h >= k >= 1. - Vincenzo Librandi, Jan 17 2013

MATHEMATICA

Select[Range[0, 200], !PrimeQ[10*# + 7]&] (* Vincenzo Librandi, Jan 12 2013 *)

PROG

(MAGMA) [n: n in [0..150] | not IsPrime(10*n + 7)]; // Vincenzo Librandi, Jan 12 2013

CROSSREFS

A102342.

Sequence in context: A138671 A286693 A032724 * A216565 A285938 A192111

Adjacent sequences:  A153305 A153306 A153307 * A153309 A153310 A153311

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Dec 23 2008

STATUS

approved

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Last modified August 19 07:12 EDT 2017. Contains 290794 sequences.