A063589 - OEIS

%I #6 Jun 26 2018 19:04:04

%S 1,11,20,12,33,41,58,87,45,76,91,106,114,136,156,150,115,140,198,190,

%T 218,189,241,231,283,254,243,311,249,275,347,345,353,294,460,361,372,

%U 496,420,431,499,424,484,546,428,449,483,558,613,540,622

%N Smallest k such that 5^k has exactly n 4's in its decimal representation.

%t a = {}; Do[k = 1; While[ Count[ IntegerDigits[5^k], 4] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a

%K base,nonn

%O 0,2

%A _Robert G. Wilson v_, Aug 10 2001

%E Name corrected by _Jon E. Schoenfield_, Jun 26 2018