[seqfan] Re: Fwd: Primes in an exponential sequence
franktaw at netscape.net
franktaw at netscape.net
Mon Feb 8 07:12:29 CET 2010
Considering that the questions of which n's have 2^n + 1 prime, and
which have 2^n - 1 prime, are both open questions after extensive study
(see Fermat primes and Mersenne primes), it is unlikely that anyone
will be able to establish definitely which numbers of this form are
prime. The most you can expect is a result of the form "searching up
to <N>, the only values were <list>".
Franklin T. Adams-Watters
-----Original Message-----
From: Olivier Gerard <olivier.gerard at gmail.com>
Perhaps someone has an idea on how to investigate this
for Vincenzo ?
---------- Forwarded message ----------
From: vincenzo.librandi at tin.it <vincenzo.librandi at tin.it>
Date: Sun, Feb 7, 2010 at 20:31
I only ask if the sequence
a(n)=2^(2*n)+2*n+1
is prime if and only if
n=3 and n=118 ?
Regards,
Vincenzo
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