A217158 a(n) is the least value of k such that the decimal expansion of n^k contains three consecutive identical digits.

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

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