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A063582 Smallest k such that 4^k has exactly n 7's in its decimal representation. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A216118 A329772 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

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Last modified July 10 16:22 EDT 2020. Contains 335577 sequences. (Running on oeis4.)