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%I #4 Jul 22 2016 10:57:11
%S 19,109,991,1009,10009,99991,9999991,1000000009,1000000000000000009,
%T 10000000000000000000009,999999999999999999999999999999991,
%U 999999999999999999999999999999999999999999991
%N Prime numbers of the form 10^k +- 9.
%C This sequence illustrates the base-n representation of numbers having the form n^k +- (n - 1).
%t Select[Sort[Flatten[Table[10^n+{9,-9},{n,50}]]],PrimeQ] (* _Harvey P. Dale_, Jul 22 2016 *)
%Y Cf. A000040, A000668, A144231, A144232, A144233, A144234, A144236, A144242, A144245
%K nonn
%O 1,1
%A _Reikku Kulon_, Sep 15 2008