A063576 Smallest k such that 4^k has exactly n 1's in its decimal representation.

1, 2, 12, 17, 29, 40, 35, 57, 112, 61, 108, 109, 101, 84, 167, 188, 182, 186, 205, 259, 252, 240, 269, 320, 329, 283, 305, 317, 300, 400, 288, 413, 458, 360, 392, 466, 447, 477, 383, 493, 481, 574, 598, 497, 567, 551, 599, 603, 676, 721, 564

Offset

0,2

Links

Robert Israel, Table of n, a(n) for n = 0..2000

Maple

N:= 100: # for a(0)..a(N)
A:= Array(0..N):
count:= 0:
for k from 1 while count < N+1 do
  v:= numboccur(1, convert(4^k, base, 10));
  if v <= N and A[v] = 0 then A[v]:= k; count:= count+1; fi
od:
convert(A, list); # Robert Israel, Jul 03 2020

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[4^k], 1] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
With[{p4=Table[DigitCount[4^n, 10, 1], {n, 750}]}, Table[Position[p4, i, 1, 1], {i, 0, 50}]]//Flatten (* Harvey P. Dale, May 05 2018 *)

Crossrefs

Cf. A000302 (powers of 4).

Sequence in context: A057827 A266802 A082407 * A144264 A277961 A294998

Adjacent sequences: A063573 A063574 A063575 * A063577 A063578 A063579

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 26 2018

Status

approved