A063577 Smallest k such that 4^k has exactly n 2's in its decimal representation.

1, 4, 9, 25, 36, 54, 45, 56, 68, 106, 87, 98, 100, 203, 140, 154, 160, 174, 165, 263, 246, 243, 157, 234, 276, 280, 338, 308, 343, 371, 335, 299, 427, 394, 497, 475, 473, 405, 524, 467, 577, 485, 586, 509, 492, 644, 464, 677, 563, 616, 582

Offset

0,2

Links

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

Mathematica

a = {}; Do[k = 1; While[ Count[ IntegerDigits[4^k], 2] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
With[{nk2=Table[{k, DigitCount[4^k, 10, 2]}, {k, 700}]}, Table[SelectFirst[nk2, #[[2]] == n&], {n, 0, 50}]][[All, 1]] (* Harvey P. Dale, Jan 21 2023 *)

Crossrefs

Sequence in context: A366243 A062503 A248648 * A087058 A046659 A063760

Adjacent sequences: A063574 A063575 A063576 * A063578 A063579 A063580

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Extensions

Name corrected by Jon E. Schoenfield, Jun 26 2018

Status

approved