|
%I #20 Dec 06 2022 07:56:35
%S 1,305,761,1357,3793,4027,85481
%N Numbers k such that 6^k + k is prime.
%C The next terms are > 12000. - _Bruno Berselli_, Sep 30 2012
%C a(8) exceeds 120,000 (from Mischa Rodermond). - _Jeppe Stig Nielsen_, Dec 05 2022
%H Henri Lifchitz and Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=6%5Ek%2Bk">PRP Top: Search for 6^k+k</a>, finds a(7).
%t Do[ If[ PrimeQ[6^n + n], Print[n] ], {n, 2500} ]
%t Select[Range[0, 4000], PrimeQ[(6^# + #)] &] (* _Vincenzo Librandi_, Sep 29 2012 *)
%o (PARI) is(n)=ispseudoprime(6^n+n) \\ _Charles R Greathouse IV_, Jun 13 2017
%K nonn
%O 1,2
%A _Robert G. Wilson v_, Jan 04 2001
%E a(5) from _Vincenzo Librandi_, Sep 29 2012
%E a(6) from _Bruno Berselli_, Sep 29 2012
%E a(7) from _Jeppe Stig Nielsen_, Dec 05 2022
| 