A063631 Smallest k such that 9^k has exactly n 5's in its decimal representation.

1, 4, 13, 23, 20, 46, 52, 35, 37, 68, 80, 103, 106, 91, 115, 138, 123, 148, 152, 137, 166, 170, 156, 199, 182, 188, 222, 225, 237, 200, 294, 292, 247, 288, 272, 289, 278, 314, 327, 328, 402, 363, 269, 312, 374, 413, 372, 407, 399, 444, 411

Offset

0,2

Links

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

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[9^k], 5] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
With[{p9=Table[{n, 9^n}, {n, 450}]}, Transpose[Table[SelectFirst[p9, DigitCount[ #[[2]], 10, 5]==i&], {i, 0, 50}]][[1]]] (* Harvey P. Dale, Nov 12 2015 *)

Crossrefs

Sequence in context: A339804 A256390 A264623 * A031240 A031320 A112263

Adjacent sequences: A063628 A063629 A063630 * A063632 A063633 A063634

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 26 2018

Status

approved