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%I #8 Sep 08 2022 08:45:51
%S 1,3,9,15,180,747,1065
%N Numbers n such that 10^n-2^n-1 is prime.
%C a(8) > 50000. - _Jens Kruse Andersen_, Aug 10 2014
%o (Magma) [n: n in [1..700] | IsPrime(10^n-2^n-1) ]
%o (PARI) is(n)=ispseudoprime(10^n-2^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. A173852.
%K nonn,hard,more
%O 1,2
%A _Vincenzo Librandi_, Mar 11 2010
%E a(6)-a(7) from _Jens Kruse Andersen_, Aug 10 2014