A063633 Smallest k such that 9^k has exactly n 7's in its decimal representation.

1, 3, 14, 19, 24, 34, 25, 50, 64, 45, 87, 56, 92, 86, 112, 150, 84, 73, 142, 140, 162, 165, 147, 196, 207, 195, 211, 278, 187, 172, 224, 234, 258, 254, 268, 291, 287, 249, 342, 306, 331, 339, 361, 309, 396, 439, 343, 391, 413, 397, 533

Offset

0,2

Links

Table of n, a(n) for n=0..50.

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[9^k], 7] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
Module[{nn=600, nk}, nk=Table[{n, DigitCount[9^n, 10, 7]}, {n, nn}]; Table[ SelectFirst[ nk, #[[2]]==k&], {k, 0, 50}]][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Nov 02 2019 *)

Crossrefs

Sequence in context: A022125 A121459 A121226 * A108933 A271384 A015639

Adjacent sequences: A063630 A063631 A063632 * A063634 A063635 A063636

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 26 2018

Status

approved