A063584 Smallest k such that 4^k has exactly n 9's in its decimal representation.

1, 6, 17, 16, 45, 56, 46, 70, 77, 86, 93, 122, 127, 173, 171, 166, 172, 214, 178, 217, 253, 300, 265, 238, 286, 266, 298, 364, 331, 343, 368, 365, 446, 447, 425, 423, 396, 483, 480, 506, 576, 575, 594, 592, 678, 579, 671, 621, 539, 664, 620

Offset

0,2

Links

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

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[4^k], 9] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
With[{n9s=DigitCount[#, 10, 9]&/@(4^Range[700])}, Flatten[Table[ Position[ n9s, n, {1}, 1], {n, 0, 50}]]] (* Harvey P. Dale, Oct 20 2013 *)

Crossrefs

Sequence in context: A200871 A112366 A095421 * A019296 A035484 A277684

Adjacent sequences: A063581 A063582 A063583 * A063585 A063586 A063587

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 26 2018

Status

approved