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

Author

Robert G. Wilson v, Aug 10 2001

Keywords

• base
• nonn

Examples

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

Links

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

Crossrefs

Essentially the same as A062520.

Cf. A000244.

Programs

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 *)

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