November 4th, 2018, 05:28 AM  #41 
Senior Member Joined: Aug 2008 From: Blacksburg VA USA Posts: 343 Thanks: 5 Math Focus: primes of course  mild guesstimate
I wonder if the values spoken of (11,23,47,2351,4703,??) will appear in the order seen in the Rowland sequence (A221869) ? Very limited dataset to make this guess, but ...

November 6th, 2018, 06:39 AM  #42  
Newbie Joined: Mar 2018 From: United States Posts: 28 Thanks: 2  Quote:
Speaking of which, we also might add that a necessary (but not sufficient) condition for odd n to be a prime is that $2^{(n1)/2}$ mod $n = n1$ $or$ $1$. In addition, in the sequence you quoted above, call it {$a_i$}, $a_{i+1}$ = $2a_ik + 1$. More about that later.  
November 7th, 2018, 06:23 AM  #43 
Newbie Joined: Mar 2018 From: United States Posts: 28 Thanks: 2  
December 23rd, 2018, 06:52 AM  #44  
Newbie Joined: Mar 2018 From: United States Posts: 28 Thanks: 2  Quote:
Quote:
The first three are Mersenne primes. In fact, the sequence is an infinite sequence of Mersenne primes, defined by $m_1 = 3$, $m_{i+1} = 2^{m_i}1$.  

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