login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A153047 Numbers n such that 2*n-15 is not a prime. 3
12, 15, 18, 20, 21, 24, 25, 27, 30, 32, 33, 35, 36, 39, 40, 42, 45, 46, 48, 50, 51, 53, 54, 55, 57, 60, 63, 65, 66, 67, 68, 69, 70, 72, 74, 75, 78, 79, 80, 81, 84, 85, 87, 88, 90, 92, 93, 95, 96, 99, 100, 101, 102, 105, 108, 109, 110, 111, 112, 114, 115, 116 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

One more than the associated entry in A153049. - R. J. Mathar, Jan 05 2011

The terms are the values of 2*h*k + k + h + 8, where h and k are positive integers.- Vincenzo Librandi, Jan 19 2013

LINKS

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

MATHEMATICA

Select[Range[12, 200], !PrimeQ[2*#-15]&] (* Vladimir Joseph Stephan Orlovsky, Feb 09 2012 *)

PROG

(MAGMA) [n: n in [10..120] | not IsPrime(2*n - 15)]; // Vincenzo Librandi, Oct 11 2012

CROSSREFS

Cf. A097480, A153043, A153045, A163657.

Sequence in context: A188766 A247542 A281880 * A265128 A243021 A164782

Adjacent sequences:  A153044 A153045 A153046 * A153048 A153049 A153050

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Dec 17 2008

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 25 21:23 EST 2021. Contains 340427 sequences. (Running on oeis4.)