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!)
A272902 Numbers n such that 6n - 5 is not prime. 0
1, 5, 9, 10, 15, 16, 20, 21, 23, 25, 29, 30, 32, 35, 37, 40, 42, 43, 44, 45, 49, 50, 51, 54, 55, 58, 60, 61, 65, 66, 68, 70, 72, 75, 76, 79, 80, 81, 83, 85, 86, 87, 89, 90, 93, 94, 95, 98, 99 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..49.

FORMULA

a(n) ~ n. - Charles R Greathouse IV, May 09 2016

EXAMPLE

a(2) = 5 because 6 * 5 - 5 = 25 that is composite.

MATHEMATICA

Select[Range[100], Not[PrimeQ[6# - 5]] &] (* Alonso del Arte, May 09 2016 *)

PROG

(PARI) is(n)=!isprime(6*n-5) \\ Charles R Greathouse IV, May 09 2016

CROSSREFS

Sequence in context: A140509 A314580 A314581 * A235033 A327593 A282757

Adjacent sequences:  A272899 A272900 A272901 * A272903 A272904 A272905

KEYWORD

nonn,easy

AUTHOR

Carlos Valencia Alonso, May 09 2016

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 August 4 20:28 EDT 2021. Contains 346455 sequences. (Running on oeis4.)