%I
%S 1,3,9,17,19,27,351,813,869,1387
%N Numbers n>0 such that 10^n+2^n+1 is prime.
%C Terms greater than 351 yield probable primes. Next term > 10000.  _Vaclav Kotesovec_, Apr 30 2014
%t Select[Range[1,1000],PrimeQ[10^#+2^#+1]&] (* _Vaclav Kotesovec_, Apr 30 2014 *)
%o (MAGMA) [n: n in [1..800]  IsPrime(10^n+2^n+1) ]
%K nonn,more
%O 1,2
%A _Vincenzo Librandi_, Mar 11 2010
%E a(8)a(10) from _Vaclav Kotesovec_, Apr 30 2014
