%I #29 Jan 16 2024 16:33:07

%S 3,7,11,83,149,223,599,647,1373,8423,149497,388897,531611,2052329

%N Prime numbers k such that (2^k + 3^k)/5 is prime.

%t Do[ If[ PrimeQ[ n ], If[ PrimeQ[ (3^n + 2^n)/5 ], Print[ n ] ] ], {n, 0, 6270} ]

%o (PARI) is(n)=isprime(n) && ispseudoprime((2^n + 3^n)/5) \\ _Charles R Greathouse IV_, Apr 28 2015

%o (Magma) [p: p in [3..1000] | IsPrime(p) and IsPrime((2^p + 3^p) div 5)]; // _Jinyuan Wang_, Dec 22 2019

%Y Cf. A127908 (primes of the form (3^k+2^k)/5).

%K nonn,more

%O 1,1

%A _Robert G. Wilson v_, Sep 09 2000

%E More terms from Kamil Duszenko (kdusz(AT)wp.pl), Apr 11 2003

%E Definition corrected by _Alexander Adamchuk_, Feb 06 2007

%E a(11) corresponding to a probable prime with 71328 digits from _Jean-Louis Charton_, Oct 14 2010

%E a(12) corresponding to a probable prime with 185551 digits from _Jean-Louis Charton_, Sep 18 2011

%E a(13) corresponding to a probable prime with 253643 digits from _Ryan Propper_, Dec 10 2023

%E a(14) corresponding to a probable prime with 979210 digits from _Ryan Propper_, Dec 10 2023