login
Numbers k such that 3*5^k + 2 is prime.
1

%I #17 Jul 09 2024 08:53:37

%S 0,1,4,5,6,10,18,30,34,53,256,304,309,400,468,766,1470,2125,2238,2404,

%T 4708,5884,6264,8676,42346

%N Numbers k such that 3*5^k + 2 is prime.

%C a(25) > 21230. - _Jinyuan Wang_, Dec 08 2019

%t Do[ If[ PrimeQ[ 3*5^n + 2 ], Print[ n ] ], {n, 0, 2000} ]

%o (PARI) is(n)=ispseudoprime(3*5^n+2) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,more

%O 1,3

%A _Robert G. Wilson v_, Nov 16 2000

%E First term 0 inserted by _Georg Fischer_, Aug 01 2019

%E a(22)-a(24) from _Jinyuan Wang_, Dec 08 2019

%E a(25) from _Michael S. Branicky_, Jul 09 2024