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A063567 4^a(n) = smallest positive power of 4 having n in its decimal representation. 2

%I

%S 5,2,4,7,1,4,2,10,7,6,5,20,25,35,9,29,2,17,15,11,28,9,36,29,5,4,9,19,

%T 24,16,11,37,38,43,35,14,8,15,7,21,6,11,16,11,9,14,21,18,10,16,26,20,

%U 30,8,14,8,4,10,25,22,22

%N 4^a(n) = smallest positive power of 4 having n in its decimal representation.

%t a = {}; Do[k = 1; While[ StringPosition[ ToString[4^k], ToString[n] ] == {}, k++ ]; a = Append[a, k], {n, 0, 50} ]; a

%t sp4[n_]:=Module[{k=1,idn=IntegerDigits[n]},While[SequenceCount[ IntegerDigits[ 4^k], idn] == 0, k++];k]; Array[sp4,70,0] (* The program uses the SequenceCount function from Mathematica version 10 *) (* _Harvey P. Dale_, Mar 12 2016 *)

%Y Essentially the same as A062521.

%K base,nonn

%O 0,1

%A _Robert G. Wilson v_, Aug 10 2001

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Last modified September 28 22:26 EDT 2020. Contains 337420 sequences. (Running on oeis4.)