%I #4 Dec 15 2017 17:37:10
%S 0,1,2,3,7,20,22,65,122,355,561,2216,5638,7271
%N Numbers n such that 10^n*(7+3*10^n)+3 is prime.
%C Values corresponding to n=5638 and n=7271 were both certified Fermat and Lucas PRPs with WinPFGW and submitted to Lifchitz's Top PRPs database.
%o (PARI) is(n)=ispseudoprime(10^n*(7+3*10^n)+3) \\ _Charles R Greathouse IV_, Jun 13 2017
%K more,nonn
%O 1,3
%A _Jason Earls_, Dec 14 2009