%I #8 Jun 26 2022 10:00:37
%S 1,6,14,15,47,31,28,44,70,49,74,93,124,128,126,130,116,156,125,175,
%T 228,207,214,201,174,264,230,241,238,266,211,370,368,279,288,305,358,
%U 366,401,385,416,387,461,466,475,429,456,428,471,470,494
%N Smallest k such that 6^k has exactly n 4's in its decimal representation.
%t a = {}; Do[k = 1; While[ Count[ IntegerDigits[6^k], 4] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
%t Module[{nn=60,k6=6^Range[500]},Table[Position[k6,_?(DigitCount[#,10,4]== n&),1,1],{n,0,nn}]]//Flatten (* _Harvey P. Dale_, Jun 26 2022 *)
%K base,nonn
%O 0,2
%A _Robert G. Wilson v_, Aug 10 2001
%E Name corrected by _Jon E. Schoenfield_, Jun 26 2018