A217180 - OEIS

A217180

a(n) is the number of digits in the decimal representation of the smallest power of n that contains five consecutive identical digits.

67, 131, 67, 88, 176, 146, 95, 131, 6, 163, 44, 253, 225, 255, 67, 290, 98, 148, 7, 138, 179, 255, 174, 131, 163, 158, 31, 239, 8, 60, 67, 242, 160, 170, 176, 32, 316, 327, 9, 192, 231, 190, 148, 240, 260, 228, 63, 146, 9, 64, 107, 206, 148, 159, 188, 250, 71

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OFFSET

2,1

COMMENTS

Number of digits in n^k is equal to floor(1 + k*log_10(n)).

LINKS

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

MATHEMATICA

Table[k = 1; While[d = IntegerDigits[n^k]; ! MemberQ[Partition[Differences[d], 4, 1], {0, 0, 0, 0}], k++]; Length[d], {n, 2, 100}] (* T. D. Noe, Oct 03 2012 *)

Table[IntegerLength[NestWhile[n #&, n, SequenceCount[IntegerDigits[#], {x_, x_, x_, x_, x_}]<1&]], {n, 2, 60}] (* Harvey P. Dale, Jun 14 2025 *)

CROSSREFS

Cf. A217160, A217170.

Sequence in context: A141925 A187990 A147100 * A144094 A044190 A044571

Adjacent sequences: A217177 A217178 A217179 * A217181 A217182 A217183

KEYWORD

nonn,base

AUTHOR

V. Raman, Sep 27 2012

STATUS

approved