OFFSET
1,1
LINKS
Ray Ballinger, Proth Search Page
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
EXAMPLE
137 * 2^3 + 1 = 1097 is a prime so 3 is in the sequence.
137 * 2^5 + 1 = 4385 = 5 * 877, so 5 is not in the sequence.
MATHEMATICA
Select[Range[1000], PrimeQ[137 2^# + 1] &] (* Alonso del Arte, Apr 06 2020 *)
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
EXTENSIONS
3 more terms sent by Jud McCranie, Jan 15 2000 and May 03 2000
One more term from Jud McCranie, Jun 12 2004
533043 from Jud McCranie, Oct 06 2004
a(20) = 2457639 from Jeppe Stig Nielsen, Apr 04 2020
STATUS
approved