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 A219461 Primes p such that 2^p - 1 is a prime with primitive root 3. 0

%I

%S 3,5,7,17,19,89,107,521

%N Primes p such that 2^p - 1 is a prime with primitive root 3.

%C If A096393(n) = 3, then A000043(n) belongs to this sequence.

%C 2^a(n) - 1 is in A001123.

%C The first term that is unknown is a(9), which is either 2203 or 2281.

%H Discussion titled <a href="http://www.mersenneforum.org/showthread.php?t=5874">Conjecture about multiplicative order of 3 modulo a Mersenne prime</a>, (postings in mersenneforum.org), starting May 14 2006.

%H <a href="/index/Pri#primes_root">Index entries for primes by primitive root</a>

%t Select[Prime@Range[98], PrimitiveRoot[2^# - 1] == 3 &]

%Y Subsequence of A000043.

%K hard,more,nonn

%O 1,1

%A _Arkadiusz Wesolowski_, Nov 20 2012

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Last modified January 22 23:50 EST 2022. Contains 350504 sequences. (Running on oeis4.)