20200708, 14:46  #1 
"murat"
May 2020
turkey
5×23 Posts 
is it possible
is it possible ( 2 ^ n ) +1 and ( 2 ) ^ ( n + 1 ) + 1 can be prime
Last fiddled with by drmurat on 20200708 at 14:46 
20200708, 15:24  #2 
"Mark"
Apr 2003
Between here and the
6331_{10} Posts 

20200708, 15:25  #3 
"murat"
May 2020
turkey
5·23 Posts 

20200708, 15:42  #4 
Sep 2002
Database er0rr
3^{3}·137 Posts 

20200708, 15:53  #5 
"murat"
May 2020
turkey
5·23 Posts 

20200708, 16:04  #6 
Sep 2002
Database er0rr
3^{3}·137 Posts 
For n > 1, N = 2^n +1 has to be a generalized Fermat prime with b=2 i.e 2^(2^a)+1, but 2^a+1 can never be a power of 2
Last fiddled with by paulunderwood on 20200708 at 16:08 
20200708, 16:25  #7 
Nov 2016
101101000100_{2} Posts 

20200708, 16:29  #8 
"murat"
May 2020
turkey
5·23 Posts 

20200708, 18:59  #9 
"murat"
May 2020
turkey
163_{8} Posts 
yes it is impossible . one of rhem is diveded by 3 all the time

20200708, 19:21  #10  
"Sam"
Nov 2016
2^{2}·3^{4} Posts 
Cunningham Chain of the second kind
Quote:
Last fiddled with by carpetpool on 20200708 at 19:22 

20200708, 19:34  #11  
"murat"
May 2020
turkey
5×23 Posts 
Quote:
(2^n) * (2^ (2n) + 1) *(2^ (2n+1) + 1) gives perfect number but it is impossible . one of them is devided by 3 
