A057469 Prime numbers k such that (2^k + 3^k)/5 is prime.

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

Offset

1,1

Links

Table of n, a(n) for n=1..14.

Mathematica

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

Prog

(PARI) is(n)=isprime(n) && ispseudoprime((2^n + 3^n)/5) \\ Charles R Greathouse IV, Apr 28 2015
(Magma) [p: p in [3..1000] | IsPrime(p) and IsPrime((2^p + 3^p) div 5)]; // Jinyuan Wang, Dec 22 2019

Crossrefs

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

Sequence in context: A016081 A287301 A105762 * A247229 A082598 A082599

Adjacent sequences: A057466 A057467 A057468 * A057470 A057471 A057472

Keyword

nonn,more

Author

Robert G. Wilson v, Sep 09 2000

Extensions

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

Definition corrected by Alexander Adamchuk, Feb 06 2007

a(11) corresponding to a probable prime with 71328 digits from Jean-Louis Charton, Oct 14 2010

a(12) corresponding to a probable prime with 185551 digits from Jean-Louis Charton, Sep 18 2011

a(13) corresponding to a probable prime with 253643 digits from Ryan Propper, Dec 10 2023

a(14) corresponding to a probable prime with 979210 digits from Ryan Propper, Dec 10 2023

Status

approved