OFFSET
1,1
EXAMPLE
If k=95 then 20*k + 1 = 1901 (prime).
PROG
(Magma) [n: n in [0..6000] | IsPrime(20*n + 1)]; // Vincenzo Librandi, Mar 26 2010
(PARI) is(n)=isprime(20*n+1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Parthasarathy Nambi, Dec 07 2006
STATUS
approved