A063580 Smallest k such that 4^k has exactly n 5's in its decimal representation.

1, 4, 8, 37, 38, 34, 72, 54, 71, 89, 99, 136, 105, 134, 151, 172, 206, 159, 202, 214, 156, 304, 274, 278, 253, 281, 268, 358, 326, 375, 389, 345, 424, 429, 460, 488, 449, 484, 466, 521, 531, 544, 568, 556, 638, 540, 590, 547, 508, 677, 606

Offset

0,2

Links

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

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[4^k], 5] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
With[{c=4^Range[700]}, Flatten[IntegerExponent[#, 4]&/@Table[Select[c, DigitCount[#, 10, 5] == n&, 1], {n, 0, 50}]]] (* Harvey P. Dale, Nov 06 2013 *)

Crossrefs

Sequence in context: A309618 A047710 A335991 * A003049 A098563 A231398

Adjacent sequences: A063577 A063578 A063579 * A063581 A063582 A063583

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 26 2018

Status

approved