OFFSET
1,1
COMMENTS
Riesel Primes with k = 3^9 = 19683.
Checked up to n = 1000000.
EXAMPLE
19683*2^4-1=314927 is a prime number.
MATHEMATICA
i=0; Table[While[i++; cp=19683*2^i-1; !PrimeQ[cp]]; i, {j, 1, 20}]
PROG
(PARI) is(n)=ispseudoprime(3^9*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Lei Zhou, Nov 08 2013
STATUS
approved