OFFSET
1,1
LINKS
Lei Zhou, Table of n, a(n) for n = 1..67
Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300
Wilfrid Keller, List of primes k.2^n - 1 for k < 300
L. Soule and K. Bonath, Riesel Prime database
MATHEMATICA
b=3^5; i=0; Table[While[i++; cp=b*2^i-1; !PrimeQ[cp]]; i, {j, 1, 33}] (* Lei Zhou, Nov 08 2013 *)
PROG
(PARI) is(n)=ispseudoprime(243*2^n-1) \\ Charles R Greathouse IV, Feb 20 2017
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
N. J. A. Sloane, Dec 29 1999
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
STATUS
approved