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Smallest power of 8 having n in its decimal representation.
2

%I #13 Apr 03 2021 15:35:07

%S 4,3,3,5,2,3,2,5,1,4,10,14,3,9,6,7,8,9,10,12,7,6,17,21,10,17,6,5,9,20,

%T 26,25,5,21,9,15,12,10,13,14,4,10,9,14,6,11,14,12,17,13,18,3,7,29,13,

%U 13,16,25,11,11,20

%N Smallest power of 8 having n in its decimal representation.

%C Variant of A062525 allowing only exponents larger than zero. [From _R. J. Mathar_, Dec 15 2008]

%H Harvey P. Dale, <a href="/A063571/b063571.txt">Table of n, a(n) for n = 0..1000</a>

%t a = {}; Do[k = 1; While[ StringPosition[ ToString[8^k], ToString[n] ] == {}, k++ ]; a = Append[a, k], {n, 0, 60} ]; a

%t sp8[n_]:=Module[{k=1},While[SequenceCount[IntegerDigits[ 8^k], IntegerDigits[ n]]<1,k++];k]; Array[sp8,70,0] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Apr 07 2017 *)

%o (Python)

%o def a(n):

%o k, pow8, s = 1, 8, str(n)

%o while s not in str(pow8): k += 1; pow8 *= 8

%o return k

%o print([a(n) for n in range(61)]) # _Michael S. Branicky_, Apr 03 2021

%K base,nonn

%O 0,1

%A _Robert G. Wilson v_, Aug 10 2001