A057464 - OEIS

%I #19 Oct 30 2024 15:39:49

%S 0,1,4,7,8,26,33,64,116,201,1278,1927,2549,4054,5379,5704,6639,13785,

%T 18918,19085

%N Numbers k such that 10*13^k + 1 is prime.

%C a(18) > 10^4. - _Jinyuan Wang_, Jan 31 2020

%t Do[ If[ PrimeQ[ 10*13^n + 1 ], Print[ n ] ], {n, 0, 1000} ]

%t Select[Range[0, 4000], PrimeQ[(10*13^# + 1)] &] (* _Vincenzo Librandi_, Sep 28 2012 *)

%o (PARI) is(n)=ispseudoprime(10*13^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,more

%O 1,3

%A _Robert G. Wilson v_, Sep 08 2000

%E a(11)-a(13) from _Vincenzo Librandi_, Sep 28 2012

%E a(14)-a(17) from _Jinyuan Wang_, Jan 31 2020

%E a(18) from _Michael S. Branicky_, May 02 2023

%E a(19)-a(20) from _Michael S. Branicky_, Oct 30 2024