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A063609
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Smallest k such that 7^k has exactly n 3's in its decimal representation.
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0
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1, 12, 3, 17, 16, 46, 27, 42, 45, 68, 91, 105, 88, 123, 111, 101, 137, 143, 151, 127, 167, 202, 217, 193, 218, 246, 238, 207, 253, 275, 235, 251, 344, 279, 347, 335, 283, 323, 378, 361, 418, 389, 421, 384, 385, 454, 471, 436, 410, 544, 522
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OFFSET
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0,2
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LINKS
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MATHEMATICA
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a = {}; Do[k = 1; While[ Count[ IntegerDigits[7^k], 3] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
With[{s=7^Range[600]}, IntegerExponent[#, 7]&/@Table[SelectFirst[s, DigitCount[ #, 10, 3]==n&], {n, 0, 50}]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 21 2016 *)
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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