OFFSET
0,2
MATHEMATICA
a = {}; Do[k = 1; While[ Count[ IntegerDigits[9^k], 4] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
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 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Robert G. Wilson v, Aug 10 2001
EXTENSIONS
Name corrected by Jon E. Schoenfield, Jun 26 2018
STATUS
approved