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A063633 Smallest k such that 9^k has exactly n 7's in its decimal representation. 0
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 (list; graph; refs; listen; history; text; internal format)
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 A108420

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

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Last modified May 6 21:35 EDT 2021. Contains 343597 sequences. (Running on oeis4.)