login
A063623
Smallest k such that 8^k has exactly n 7's in its decimal representation.
0
1, 5, 9, 8, 44, 25, 51, 59, 61, 74, 76, 79, 99, 94, 120, 117, 115, 143, 163, 148, 139, 194, 178, 211, 203, 157, 158, 272, 218, 217, 270, 285, 307, 337, 314, 334, 260, 322, 299, 354, 344, 479, 327, 385, 401, 389, 408, 455, 445, 430, 400
OFFSET
0,2
MATHEMATICA
a = {}; Do[k = 1; While[ Count[ IntegerDigits[8^k], 7] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
With[{n8=Table[DigitCount[8^n, 10, 7], {n, 0, 500}]}, Join[{1}, Flatten[ Table[ Position[ n8, i, {1}, 1], {i, 50}]]-1]] (* Harvey P. Dale, Apr 10 2016 *)
CROSSREFS
Sequence in context: A244249 A353602 A123600 * A085566 A076390 A321632
KEYWORD
base,nonn
AUTHOR
Robert G. Wilson v, Aug 10 2001
EXTENSIONS
Name corrected by Jon E. Schoenfield, Jun 26 2018
STATUS
approved