A063586 Smallest k such that 5^k has exactly n 1's in its decimal representation.

1, 3, 9, 22, 36, 26, 33, 65, 92, 82, 54, 111, 89, 105, 131, 146, 149, 189, 187, 212, 192, 204, 182, 200, 252, 210, 307, 247, 268, 304, 300, 338, 313, 333, 404, 417, 363, 421, 355, 433, 485, 481, 451, 458, 521, 505, 551, 489, 497, 575, 608

Offset

0,2

Links

Robert Israel, Table of n, a(n) for n = 0..2800

Maple

N:= 100: # to get a(0)..a(N)
V:= Array(0..N): count:= 0:
for n from 0 while count < N do
  v:= numboccur(1, convert(5^n, base, 10));
  if v <= N and V[v] = 0 then
     count:= count+1; V[v]:= n;
  fi;
od:
convert(V, list); # Robert Israel, Apr 07 2019

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[5^k], 1] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
Join[{1, 3}, With[{k=5^Range[0, 2000]}, Flatten[Table[Position[k, _?(DigitCount[ #, 10, 1]==n&), 1, 1], {n, 2, 100}]]]-1] (* Much faster than above program  but Range constant may limit accuracy if more terms are sought. *) (* Harvey P. Dale, Jul 18 2019 *)

Crossrefs

Sequence in context: A247182 A363967 A318807 * A131477 A002128 A379177

Adjacent sequences: A063583 A063584 A063585 * A063587 A063588 A063589

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 26 2018

Status

approved