A063613 Smallest k such that 7^k has exactly n 7's in its decimal representation.

2, 1, 14, 11, 26, 29, 49, 33, 67, 81, 84, 96, 101, 95, 89, 132, 163, 160, 137, 152, 185, 177, 195, 230, 205, 188, 214, 267, 274, 288, 325, 307, 286, 285, 270, 311, 324, 353, 318, 336, 309, 329, 403, 375, 432, 436, 447, 479, 401, 459, 491

Offset

0,1

Links

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

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[7^k], 7] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
Module[{p7=DigitCount[#, 10, 7]&/@(7^Range[500])}, Table[Position[p7, n, {1}, 1], {n, 0, 50}]]//Flatten (* Harvey P. Dale, Apr 08 2017 *)

Crossrefs

Sequence in context: A187920 A307804 A338207 * A245733 A276851 A080346

Adjacent sequences: A063610 A063611 A063612 * A063614 A063615 A063616

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 26 2018

Status

approved