OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
FORMULA
a(k) = (A030433(k) + 1)/10. - R. J. Mathar, Jul 08 2009
EXAMPLE
If n = 2, then 10*n - 1 = 19 (prime).
If n = 18, then 10*n - 1 = 179 (prime).
If n = 36, then 10*n - 1 = 359 (prime).
MAPLE
a:= proc(n) if isprime(10*n-1) then n end if end proc: seq(a(n), n = 1 .. 200); # Emeric Deutsch, Aug 02 2009
MATHEMATICA
Select[Range[200], PrimeQ[10# - 1] &] (* Alonso del Arte, Feb 09 2014 *)
PROG
(Magma) [n: n in [1..200]| IsPrime(10*n-1)] // Vincenzo Librandi, Feb 10 2014
(PARI) is(n)=isprime(10*n-1) \\ Charles R Greathouse IV, Jun 12 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Parthasarathy Nambi, Apr 03 2005
EXTENSIONS
Extended by Emeric Deutsch, Aug 02 2009
STATUS
approved