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 A063578 Smallest k such that 4^k has exactly n 3's in its decimal representation. 1

%I

%S 1,7,26,43,38,57,48,64,81,92,91,78,104,151,155,143,162,150,173,249,

%T 267,251,339,282,333,325,275,378,345,428,415,429,473,463,411,430,513,

%U 420,507,546,508,489,533,603,566,593,641,545,707,638,722

%N Smallest k such that 4^k has exactly n 3's in its decimal representation.

%H Robert Israel, <a href="/A063578/b063578.txt">Table of n, a(n) for n = 0..1000</a>

%p N:= 100: # to get a(0) to a(N)

%p A:= Array(0..N):

%p count:= 0:

%p for n from 1 while count < N+1 do

%p v:= numboccur(3, convert(4^n,base,10));

%p if v <= N and A[v] = 0 then

%p count:= count+1;

%p A[v]:= n;

%p fi

%p od:

%p seq(A[i],i=0..N); # _Robert Israel_, Feb 24 2016

%t a = {}; Do[k = 1; While[ Count[ IntegerDigits[4^k], 3] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a

%Y Cf. A063576, A063577, A063579, A063580, A063581, A063582, A063583, A063584.

%K base,nonn

%O 0,2

%A _Robert G. Wilson v_, Aug 10 2001

%E Name corrected by _Jon E. Schoenfield_, Jun 26 2018

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Last modified August 14 07:04 EDT 2020. Contains 336477 sequences. (Running on oeis4.)