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Numbers n such that 41^n + 2 is prime.
1

%I #28 Sep 08 2022 08:46:10

%S 0,1,9,23,681,2487

%N Numbers n such that 41^n + 2 is prime.

%C All terms > 0 are odd. - _Robert Israel_, Sep 29 2014

%C a(7) > 2*10^5. - _Robert Price_, May 08 2015

%t Select[Range[0, 2000], PrimeQ[41^# + 2] &]

%o (Magma) [n: n in [0..600]| IsPrime( 41^n + 2 )];

%o (PARI) is(n)=ispseudoprime(41^n+2) \\ _Charles R Greathouse IV_, Jun 13 2017

%Y Cf. similar sequences listed in A247957.

%K nonn,more

%O 1,3

%A _Vincenzo Librandi_, Sep 29 2014