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%I #7 Jun 26 2018 19:21:21
%S 2,1,13,21,29,65,66,56,69,114,101,112,137,165,172,219,233,185,252,299,
%T 268,261,322,394,310,345,435,329,405,500,498,427,395,517,586,555,548,
%U 590,596,574,578,531,717,661,689,732,669,789,718,875,834
%N Smallest k such that 3^k has exactly n 3's in its decimal representation.
%t a = {}; Do[k = 1; While[ Count[ IntegerDigits[3^k], 3] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
%t Flatten[With[{t=3^Range[900]},Table[Position[t,_?(DigitCount[#,10,3]==n&),1,1],{n,0,50}]]] (* _Harvey P. Dale_, Feb 22 2013 *)
%K base,nonn
%O 0,1
%A _Robert G. Wilson v_, Aug 10 2001
%E Name corrected by _Jon E. Schoenfield_, Jun 26 2018
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