login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A153347 Numbers n>0 such that 7*n-4 is not prime. 1
2, 4, 6, 7, 8, 10, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 30, 31, 32, 34, 36, 37, 38, 40, 42, 43, 44, 46, 47, 48, 49, 50, 52, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 70, 71, 72, 73, 74, 76, 77, 78, 79, 80, 82, 84, 85, 86, 87, 88, 90, 91, 92 (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 odd terms in the following triangular array:

*;

*,*;

*,*,*;

*,7,*,*;

*,*,*,*,*;

*,*,*,*,21,*;

7,*,*,*,*,*,*;

*,*,*,*,*,*,37,*;

*,*,*,25,*,*,*,*,*;

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

*,17,*,*,*,*,*,*,63,*,*;

*,*,*,*,*,47,*,*,*,*,*,*;

*,*,*,*,43,*,*,*,*,*,*,97,*;

13,*,*,*,*,*,*,71,*,*,*,*,*,*; etc.

where * marks the non-integer values of (4*h*k + 2*k + 2*h + 5)/7 with h >= k >= 1. - Vincenzo Librandi, Jan 17 2013

MATHEMATICA

Select[Range[1, 200], !PrimeQ[7 # - 4]&] (* Vincenzo Librandi, Jan 13 2013 *)

PROG

(Magma) [n: n in [1..150] | not IsPrime(7*n-4)]; // Vincenzo Librandi, Jan 13 2013

CROSSREFS

Cf. A024903.

Sequence in context: A138204 A080645 A024413 * A330945 A153167 A227187

Adjacent sequences: A153344 A153345 A153346 * A153348 A153349 A153350

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Dec 24 2008

EXTENSIONS

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

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 2 12:07 EST 2022. Contains 358493 sequences. (Running on oeis4.)