OFFSET
1,1
COMMENTS
2^a(n) - 1 is in A001123.
a(12) >= 21701. - Max Alekseyev, Feb 08 2024
LINKS
Discussion titled Conjecture about multiplicative order of 3 modulo a Mersenne prime, (postings in mersenneforum.org), starting May 14 2006.
MATHEMATICA
Select[Prime@Range[98], PrimitiveRoot[2^# - 1] == 3 &]
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
Arkadiusz Wesolowski, Nov 20 2012
EXTENSIONS
a(9)-a(11) from Max Alekseyev, Feb 07 2024
STATUS
approved