|
%I #10 Sep 08 2022 08:45:53
%S 13,193,1993,19993,1999993,19999999999999993,1999999999999999999993,
%T 19999999999999999999999999993,
%U 1999999999999999999999999999999999999999999999993,19999999999999999999999999999999999999999999999999999999999999999999999999999999993
%N Primes of the form 2*10^n-7.
%t Select[2*10^Range[100]-7, PrimeQ] (* _Harvey P. Dale_, Jan 27 2015 *)
%o (Magma)[a: n in [1..250]|IsPrime(a) where a is (2*10^n-7)]
%Y Cf. A102946.
%K nonn
%O 1,1
%A _Vincenzo Librandi_, Dec 11 2010
%E One more term (a(10)) from _Harvey P. Dale_, Jan 27 2015
| 