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A217187
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a(n) is the number of digits in the decimal representation of the smallest power of 5 that contains n consecutive identical digits.
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0
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1, 8, 35, 67, 88, 760, 1948, 1951, 1955, 1956, 1959, 1960
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OFFSET
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1,2
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COMMENTS
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Number of digits in 5^k is equal to floor(1 + k*log_10(5)).
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LINKS
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MATHEMATICA
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k = 0; Join[{1}, Table[While[d = IntegerDigits[5^k]; prt = Partition[Differences[d], n - 1, 1]; ! MemberQ[prt, Table[0, {n - 1}]], k++]; Length[d], {n, 2, 8}]] (* T. D. Noe, Oct 03 2012 *)
Module[{nn=3000, p5}, p5=5^Range[nn]; Table[IntegerLength[SelectFirst[p5, SequenceCount[ IntegerDigits[ #], PadRight[{}, n, x_]]>0&]], {n, 12}]] (* Harvey P. Dale, Aug 27 2023 *)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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