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Primes of the form (5^k-1)/4 or (5^k+3)/4.
1

%I #12 Jul 05 2024 08:13:07

%S 2,7,31,157,3907,19531,2441407,12207031,61035157,305175781,

%T 9313225746154785157,177635683940025046467781066894531

%N Primes of the form (5^k-1)/4 or (5^k+3)/4.

%H Amiram Eldar, <a href="/A088554/b088554.txt">Table of n, a(n) for n = 1..19</a>

%t With[{kmax = 100}, Select[Flatten[Table[(5^k + {-1, 3})/4, {k, 0, kmax}]], PrimeQ]] (* _Amiram Eldar_, Jul 05 2024 *)

%Y Cf. A004061.

%K nonn

%O 1,1

%A _Cino Hilliard_, Nov 17 2003

%E Edited by _Don Reble_, May 03 2006