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A217159
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a(n) is the least value of k such that the decimal expansion of n^k contains four consecutive identical digits.
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3
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41, 33, 90, 95, 115, 71, 60, 88, 4, 39, 18, 25, 14, 98, 45, 52, 78, 70, 4, 29, 42, 35, 41, 48, 44, 11, 21, 37, 4, 18, 36, 71, 34, 18, 64, 20, 39, 32, 4, 40, 20, 20, 45, 33, 33, 14, 36, 40, 4, 37, 42, 29, 39, 63, 24, 10, 26, 10, 4, 64, 15, 30, 30, 18, 17, 58
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OFFSET
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2,1
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LINKS
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MATHEMATICA
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Table[k = 1; While[! MemberQ[Partition[Differences[IntegerDigits[n^k]], 3, 1], {0, 0, 0}], k++]; k, {n, 2, 100}] (* T. D. Noe, Oct 01 2012 *)
lk[n_]:=Module[{k=1, t=Table[x_, 4]}, While[SequenceCount[IntegerDigits[n^k], t]< 1, k++]; k]; Array[lk, 80, 2] (* Harvey P. Dale, Jun 21 2022 *)
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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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