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%I #16 Sep 08 2022 08:45:51
%S 1,5,11,14,19,55,101,560,805,3188,4441,25733,37501
%N Numbers n such that 10^n-2*n-1 is prime
%C a(14) > 10^5. - _Robert Price_, Mar 13 2015
%t Select[Range[5000], PrimeQ[(10^# - 2*# - 1)] &] (* _Vincenzo Librandi_, Oct 05 2012 *)
%o (Magma) [n: n in [1..550] | IsPrime(10^n-2*n-1) ]
%o (PARI) for(n=1, 999, ispseudoprime(10^n-2*n-1) && print1(n", ")) \\ _M. F. Hasler_, Aug 06 2011
%Y Cf. A173839.
%Y Cf. A110065, A110066, A110067, A173837, A174176.
%K nonn
%O 1,2
%A _Vincenzo Librandi_, Mar 11 2010
%E a(10)-a(11) from _Vincenzo Librandi_, Oct 05 2012
%E a(12)-a(13) from _Robert Price_, Mar 13 2015
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