A058829 - OEIS

%I #25 Dec 11 2022 15:08:54

%S 1,19,43,607,889,3727,12229,124433,246229

%N Numbers k such that 6^k - k is prime.

%C a(8) > 30000. - _Giovanni Resta_, Apr 07 2013

%C a(9) > 2*10^5. - _Robert Price_, Jan 21 2014

%t Do[ If[ PrimeQ[6^n - n], Print[n] ], {n, 2500} ]

%t Select[Range[4000], PrimeQ[(6^# - #)] &] (* _Vincenzo Librandi_, Sep 29 2012 *)

%o (PARI) is(n)=ispseudoprime(6^n-n) \\ _Charles R Greathouse IV_, Feb 20 2017

%Y Cf. A024063 (6^n-n).

%K nonn,hard,more

%O 1,2

%A _Robert G. Wilson v_, Jan 04 2001

%E a(6) from _Vincenzo Librandi_, Sep 29 2012

%E a(7) from _Giovanni Resta_, Apr 07 2013

%E a(8) from _Robert Price_, Jan 21 2014

%E a(9) from _Ryan Propper_, Dec 11 2022