%I
%S 1,2,3,4,372
%N Numbers n such that 10^4n + 10^3n  10^n  3 is prime.
%C Corresponds to the numbers 10987, 100999897, 1000999998997, 10000999999989997, ...
%t fQ[n_] := PrimeQ[10^(4 n) + 10^(3 n)  10^n  3]; k = 1; lst = {}; While[k < 3300, If[ fQ@k, AppendTo[lst, k]]; k++ ]; lst (* _Robert G. Wilson v_, Feb 15 2010 *)
%o (PARI) is(n)=ispseudoprime(10^4*n+10^3*n10^n3) \\ _Charles R Greathouse IV_, Jun 13 2017
%K nonn
%O 1,2
%A _James G. Merickel_, Feb 07 2010
