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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A217179 a(n) is the number of digits in the decimal representation of the smallest power of n that contains four consecutive identical digits.

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%I A217179 #13 Jul 01 2021 17:45:17
%S A217179 13,16,55,67,90,61,55,84,5,41,20,28,17,116,55,64,98,90,6,39,57,48,57,
%T A217179 68,63,16,31,55,6,27,55,108,53,28,100,32,62,51,7,65,33,33,74,55,55,24,
%U A217179 61,68,7,64,73,51,68,110,42,18,46,18,8,115,27,54,55,33,31,106
%N A217179 a(n) is the number of digits in the decimal representation of the smallest power of n that contains four consecutive identical digits.
%C A217179 Number of digits in n^k is equal to floor(1 + k*log_10(n)).
%H A217179 V. Raman, <a href="/A217179/b217179.txt">Table of n, a(n) for n = 2..10000</a>
%t A217179 Table[k = 1; While[d = IntegerDigits[n^k]; ! MemberQ[Partition[Differences[d], 3, 1], {0, 0, 0}], k++]; Length[d], {n, 2, 100}] (* _T. D. Noe_, Oct 03 2012 *)
%t A217179 ndsp[n_]:=Module[{k=1},While[SequenceCount[IntegerDigits[n^k],{x_,x_,x_,x_}] <1,k++];IntegerLength[n^k]]; Array[ndsp,70,2] (* _Harvey P. Dale_, Jul 01 2021 *)
%Y A217179 Cf. A217159, A217169.
%K A217179 nonn,base
%O A217179 2,1
%A A217179 _V. Raman_, Sep 27 2012