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A217158 a(n) is the least value of k such that the decimal expansion of n^k contains three consecutive identical digits. 3
24, 32, 12, 50, 5, 31, 8, 16, 3, 8, 17, 25, 14, 23, 6, 12, 6, 9, 3, 11, 7, 15, 14, 25, 11, 11, 10, 5, 3, 7, 8, 10, 10, 18, 9, 15, 2, 12, 3, 14, 4, 7, 12, 18, 12, 8, 17, 17, 3, 15, 10, 7, 11, 25, 24, 8, 11, 10, 3, 14, 11, 18, 4, 7, 9, 13, 7, 12, 3, 11, 8, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

V. Raman, Table of n, a(n) for n = 2..10000

MATHEMATICA

Table[k = 1; While[! MemberQ[Partition[Differences[IntegerDigits[n^k]], 2, 1], {0, 0}], k++]; k, {n, 2, 100}] (* T. D. Noe, Oct 01 2012 *)

lvk[n_]:=Module[{k=1}, While[SequenceCount[IntegerDigits[n^k], {x_, x_, x_}]<1, k++]; k]; Array[lvk, 80, 2] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 13 2018 *)

CROSSREFS

Cf. A045875, A215727, A215728, A215729, A215730, A215731.

Sequence in context: A161378 A206448 A266984 * A214227 A337055 A064673

Adjacent sequences:  A217155 A217156 A217157 * A217159 A217160 A217161

KEYWORD

nonn,base

AUTHOR

V. Raman, Sep 27 2012

STATUS

approved

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Last modified September 17 01:35 EDT 2021. Contains 347477 sequences. (Running on oeis4.)