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A063592 Smallest k such that 5^k has exactly n 7's in its decimal representation. 0
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 (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[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

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Last modified April 8 04:26 EDT 2020. Contains 333312 sequences. (Running on oeis4.)