A063566 3^a(n) = smallest positive power of 3 having n in its decimal representation.

10, 4, 3, 1, 5, 8, 8, 3, 4, 2, 21, 19, 17, 22, 11, 13, 17, 11, 7, 9, 18, 7, 19, 13, 5, 26, 19, 3, 24, 6, 16, 12, 13, 31, 15, 21, 24, 29, 18, 31, 17, 12, 18, 5, 12, 28, 16, 11, 15, 10, 35, 32, 33, 12, 26, 27, 8, 40, 26, 10, 21, 8, 19, 17, 24, 8, 33, 16, 9, 14

Offset

0,1

Links

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Example

a(2) = a(7) = a(27) = 3 because 3^3 = 27.

Mathematica

a = {}; Do[k = 1; While[ StringPosition[ ToString[3^k], ToString[n] ] == {}, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
sp3[n_]:=Module[{idn=IntegerDigits[n], t=1}, While[!MemberQ[Partition[ IntegerDigits[ 3^t], Length[idn], 1], idn], t++]; t]; Array[sp3, 60, 0] (* Harvey P. Dale, Oct 29 2013 *)

Prog

(Python)
def a(n):
    s, k = str(n), 1
    while s not in str(3**k): k += 1
    return k
print([a(n) for n in range(70)]) # Michael S. Branicky, Oct 04 2021

Crossrefs

Essentially the same as A062520.

Cf. A000244.

Sequence in context: A065194 A113315 A081986 * A153690 A018811 A309707

Adjacent sequences: A063563 A063564 A063565 * A063567 A063568 A063569

Keyword

base,nonn

Author

Robert G. Wilson v, Aug 10 2001

Status

approved