A063592 Smallest k such that 5^k has exactly n 7's in its decimal representation.

1, 7, 15, 34, 31, 61, 42, 55, 74, 82, 96, 134, 110, 127, 111, 160, 164, 126, 141, 194, 247, 250, 223, 255, 269, 281, 258, 292, 378, 321, 276, 340, 435, 418, 407, 412, 425, 475, 365, 422, 462, 476, 533, 479, 495, 429, 538, 526, 543, 542, 625

Offset

0,2

Links

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

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[5^k], 7] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
nn=60; With[{c=DigitCount[#, 10, 7]&/@(5^Range[20nn])}, Flatten[ Table[ Position[c, n, 1, 1], {n, 0, nn}]]] (* Harvey P. Dale, Apr 01 2012 *)

Crossrefs

Sequence in context: A291642 A271995 A174792 * A159792 A247606 A146837

Adjacent sequences: A063589 A063590 A063591 * A063593 A063594 A063595

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 26 2018

Status

approved