A063582 Smallest k such that 4^k has exactly n 7's in its decimal representation.

1, 10, 15, 12, 23, 60, 58, 76, 83, 85, 114, 130, 151, 141, 180, 107, 174, 190, 249, 187, 248, 220, 212, 269, 287, 297, 237, 316, 327, 370, 405, 383, 416, 313, 424, 412, 390, 483, 512, 496, 479, 502, 596, 578, 626, 581, 612, 593, 446, 587, 600

Offset

0,2

Links

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

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[4^k], 7] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a

Crossrefs

Sequence in context: A329772 A343961 A289361 * A074391 A324527 A164865

Adjacent sequences: A063579 A063580 A063581 * A063583 A063584 A063585

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 26 2018

Status

approved