OFFSET
0,2
MATHEMATICA
a = {}; Do[k = 1; While[ Count[ IntegerDigits[7^k], 5] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
Join[{1}, With[{p7=7^Range[0, 500]}, Flatten[Table[Position[p7, _?(DigitCount[ #, 10, 5]==n&), {1}, 1], {n, 50}]]-1]] (* Harvey P. Dale, Sep 17 2013 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Robert G. Wilson v, Aug 10 2001
EXTENSIONS
Name corrected by Jon E. Schoenfield, Jun 26 2018
STATUS
approved