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%I #22 Oct 13 2024 14:02:59
%S 3,5,41,357,395,479,645,2637,8853,11529,20087,27443,30635
%N Numbers k such that 10^k + 109 is prime.
%C a(14) > 50000. - _Michael S. Branicky_, Oct 13 2024
%e For n = 3, a(3) = 10^3 + 109 = 1109, which is prime.
%t Select[Range[3000], PrimeQ[10^# + 109] &]
%o (Magma) [n: n in [1..400] | IsPrime(10^n+109)];
%o (PARI) is(n)=ispseudoprime(10^n+109) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. similar sequences listed in A258932.
%K nonn,more
%O 1,1
%A _Vincenzo Librandi_, Jun 15 2015
%E a(9)-a(13) from _Jens Kruse Andersen_, Jun 23 2015