%I #15 Feb 08 2024 01:49:37
%S 2,3,3,3,17,3,3,7,37,3,3,43,3,5,5,3,3,23,3,7
%N Least primitive root of n-th Mersenne prime.
%H Joerg Arndt, <a href="http://www.jjj.de/fxt/#fxtbook">Matters Computational (The Fxtbook)</a>
%H GIMPS, <a href="http://mersenne.org/">Great Internet Mersenne Prime Search</a>
%H S. S. Wagstaff, Jr., <a href="http://www.cerias.purdue.edu/homes/ssw/cun/index.html">The Cunningham Project</a>
%e a(5)=17 because 17 is the least primitive root of the 5th Mersenne prime, 8191.
%Y Cf. A000668, A000043.
%K hard,more,nonn
%O 1,1
%A _Ken Takusagawa_, Aug 05 2004
%E a(16), a(18)-a(20) from _Max Alekseyev_, Feb 07 2024