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Numbers k such that k^5 + 4^k is prime.
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%I #22 Oct 22 2024 09:48:27

%S 1,3,7,9,37,99,319,6559,7249,18327,66663

%N Numbers k such that k^5 + 4^k is prime.

%C a(12) > 10^5. - _Michael S. Branicky_, Oct 22 2024

%t Select[Range[10000], PrimeQ[#^5 + 4^#] &] (* _Vincenzo Librandi_, Oct 04 2012 *)

%o (PARI) is(n)=ispseudoprime(n^5+4^n) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,more

%O 1,2

%A _Zak Seidov_, Oct 17 2002

%E More terms from _Ralf Stephan_, Mar 25 2003

%E a(8)-a(9) from _Vincenzo Librandi_, Oct 04 2012

%E a(10) from _Michael S. Branicky_, Jul 13 2023

%E a(11) from _Michael S. Branicky_, Oct 22 2024