|
%I #9 Jun 26 2018 19:11:02
%S 1,5,6,10,30,29,43,45,36,73,75,92,68,116,102,85,98,141,166,151,109,
%T 154,172,196,175,176,217,244,245,207,275,226,242,289,269,263,297,261,
%U 326,296,355,335,369,336,412,414,360,458,394,457,404
%N Smallest k such that 9^k has exactly n 4's in its decimal representation.
%t a = {}; Do[k = 1; While[ Count[ IntegerDigits[9^k], 4] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
%t With[{ns=9^Range[500]},Log[9,#]&/@Flatten[Table[Select[ns,Count[ IntegerDigits[#],4]==n&,1],{n,0,50}]]] (* _Harvey P. Dale_, Oct 20 2011 *)
%K base,nonn
%O 0,2
%A _Robert G. Wilson v_, Aug 10 2001
%E Name corrected by _Jon E. Schoenfield_, Jun 26 2018
|
