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Primes of the form (3^k-1)/2 or (3^k+1)/2.
4

%I #14 Jul 05 2024 07:30:57

%S 2,5,13,41,1093,797161,21523361,926510094425921,

%T 1716841910146256242328924544641,3754733257489862401973357979128773,

%U 6957596529882152968992225251835887181478451547013

%N Primes of the form (3^k-1)/2 or (3^k+1)/2.

%C The next term is too large to include.

%C The next term has 258 digits. - _Harvey P. Dale_, Dec 04 2018

%H Amiram Eldar, <a href="/A088553/b088553.txt">Table of n, a(n) for n = 1..15</a>

%t Select[Flatten[Table[(3^x+{1,-1})/2,{x,150}]],PrimeQ] (* _Harvey P. Dale_, Dec 04 2018 *)

%Y Cf. A028491, A096723, A171381.

%K nonn

%O 1,1

%A _Cino Hilliard_, Nov 17 2003

%E Edited by _Don Reble_, May 03 2006