OFFSET
0,2
MATHEMATICA
a = {}; Do[k = 1; While[ Count[ IntegerDigits[7^k], 9] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
With[{sev=Table[DigitCount[7^n, 10, 9], {n, 600}]}, Table[Position[sev, i, {1}, 1], {i, 0, 50}]]//Flatten (* Harvey P. Dale, May 04 2016 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Robert G. Wilson v, Aug 10 2001
EXTENSIONS
Name corrected by Jon E. Schoenfield, Jun 26 2018
STATUS
approved