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%I #18 Feb 25 2021 19:39:26
%S 0,1,105,369,25521
%N Numbers n such that 17^n + 2 is prime.
%C Only numbers of the form 6k-5 and 6k-3 need be tested.
%C No further terms < 100000. - _Ray Chandler_, Jul 31 2011
%C a(6) > 2*10^5. - _Robert Price_, Oct 23 2014
%H Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=17%5En%2B2&action=Search">PRP Records</a>.
%t Do[If[PrimeQ[17^n + 2], Print[n]], {n, 0, 2500}] (* _Stefan Steinerberger_, Jan 28 2006 *)
%t Join[{0},
%t Select[Flatten[Table[6 n - {5, 3}, {n, 5000}]], PrimeQ[17^# + 2] &]] (* _Harvey P. Dale_, Feb 25 2021 *)
%o (PARI) g2(n)= { print1(0","); forstep(x=1,n,6, if(ispseudoprime(17^x+2),print1(x",")); if(ispseudoprime(17^(x+2)+2),print1(x+2",")) ) }
%K nonn
%O 1,3
%A _Cino Hilliard_, Jan 09 2006
%E 25521 from _Ray Chandler_, Jul 30 2011