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%I #8 Sep 08 2022 08:45:50
%S 7,99989,99999999977,99999999999971,9999999999999999961,
%T 9999999999999999999999999999999999999999999999999999889,
%U 99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999797
%N Primes of the form 10^n - 2*n - 1.
%H Vincenzo Librandi, <a href="/A173839/b173839.txt">Table of n, a(n) for n = 1..9</a>
%t Select[Table[10^n - 2*n - 1, {n, 0, 200}], PrimeQ] (* _Vincenzo Librandi_, Dec 01 2012 *)
%o (Magma) [a: n in [0..200] | IsPrime(a) where a is 10^n - 2*n - 1]; // _Vincenzo Librandi_, Dec 01 2012
%Y Cf. A174177.
%K nonn
%O 1,1
%A _Vincenzo Librandi_, Feb 26 2010