OFFSET
1,2
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
KEYWORD
nonn,easy
AUTHOR
Carlos Valencia Alonso, May 09 2016
STATUS
approved