%I
%S 17,197,1997,19997,19999999999997,199999999999997,
%T 19999999999999999999999999999999999999999999999999999999999999999999999999997
%N Primes of the form 2*10^n  3.
%C a(8) has 238 digits, a(9) has 873 digits and a(10) has 989 digits.
%t Select[Table[FromDigits[Join[{1},PadLeft[{},n,9],{7}]],{n,0,1000}],PrimeQ] (* _Harvey P. Dale_, Oct 30 2011 *)
%o (MAGMA) [a: n in [0..250]  IsPrime(a) where a is 2*10^n3];
%Y Cf. A102947.
%K nonn
%O 1,1
%A _Vincenzo Librandi_, Dec 10 2010
