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A063429
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Smallest k such that 2^k has exactly n 3's in its decimal representation.
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9
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1, 5, 49, 25, 35, 109, 96, 128, 135, 169, 182, 156, 208, 302, 310, 277, 221, 300, 346, 498, 387, 502, 563, 507, 503, 611, 550, 585, 615, 681, 731, 817, 819, 835, 779, 860, 849, 840, 879, 997, 1016, 925, 1066, 1161, 1117, 1186, 1282, 1090, 1293, 1251, 1444
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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[2^k], 3] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a
With[{dr=Table[{k, DigitCount[2^k, 10, 3]}, {k, 1500}]}, Table[SelectFirst[dr, #[[2]]==n&], {n, 0, 50}]][[;; , 1]] (* Harvey P. Dale, Jul 30 2023 *)
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PROG
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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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