

A154611


Numbers n such that 7*n+3 is not prime.


1



1, 3, 5, 6, 7, 9, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21, 23, 24, 25, 26, 27, 29, 30, 31, 33, 35, 36, 37, 39, 41, 42, 43, 45, 46, 47, 48, 49, 51, 53, 54, 55, 56, 57, 59, 60, 61, 62, 63, 64, 65, 66, 67, 69, 70, 71, 72, 73, 75, 76, 77, 78, 79
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OFFSET

1,2


COMMENTS

The even terms are the integer values of (4*h*k + 2*k + 2*h  2)/7, where h and k are positive integers.  Vincenzo Librandi, Jan 17 2013
The corresponding composite numbers are 10, 24, 38, 45, 52, 66, 80, 87, 94, 108, 115, 122, 129, ...  Michael B. Porter, Jan 17 2013


LINKS

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


MATHEMATICA

With[{nn=100}, Sort[Join[Range[1, nn1, 2], Select[Range[0, nn, 2], !PrimeQ[ 7#+3]&]]]] (* Harvey P. Dale, Aug 22 2012 *)
Select[Range[0, 100], !PrimeQ[7 # + 3]&] (* Vincenzo Librandi, Apr 05 2013 *)


PROG

(Magma) [n: n in [0..80]  not IsPrime(7*n+3)]; // Vincenzo Librandi, Apr 05 2013


CROSSREFS

Cf. A089033, A045437, A017017.
Sequence in context: A103826 A079905 A321321 * A189669 A164028 A301729
Adjacent sequences: A154608 A154609 A154610 * A154612 A154613 A154614


KEYWORD

nonn,easy


AUTHOR

Vincenzo Librandi, Jan 15 2009


EXTENSIONS

Erroneous comments deleted by N. J. A. Sloane, Jun 23 2010


STATUS

approved



