%I #23 Jun 19 2020 21:28:07
%S 0,106,104,104,105,102,102,408,104,107,203,109,103,103,1056,3703,4604,
%T 207,606,11018,3069,20064
%N Least number k with at least one zero such that k^n contains no zero, or 0 if no such number exists.
%C a(n) > 5*10^8 or 0 for n = 23 and for 25 < n < 75.
%C It is known that a(24) = 12801714 and a(25) = 402.
%C a(n) > 5*10^9 or 0 for n = 23 and for 25 < n <= 200.  _Chai Wah Wu_, Apr 25 2019
%e a(5) = 105 because 105 is the smallest number with a 0 where 105^5 does not have a 0 (105^5 = 12762815625).
%o (Python)
%o def f(x):
%o for n in range(10**7):
%o if "0" in str(n):
%o if "0" not in str(n**x):
%o return n
%o for x in range(1, 75):
%o if f(x) is None:
%o print(0)
%o else:
%o print(f(x))
%Y Cf. A104315.
%K nonn,base,more,hard
%O 1,2
%A _Derek Orr_, Jan 02 2014
