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.
%I A217187 #7 Aug 27 2023 14:21:03
%S A217187 1,8,35,67,88,760,1948,1951,1955,1956,1959,1960
%N A217187 a(n) is the number of digits in the decimal representation of the smallest power of 5 that contains n consecutive identical digits.
%C A217187 Number of digits in 5^k is equal to floor(1 + k*log_10(5)).
%t A217187 k = 0; Join[{1}, Table[While[d = IntegerDigits[5^k]; prt = Partition[Differences[d], n - 1, 1]; ! MemberQ[prt, Table[0, {n - 1}]], k++]; Length[d], {n, 2, 8}]] (* _T. D. Noe_, Oct 03 2012 *)
%t A217187 Module[{nn=3000,p5},p5=5^Range[nn];Table[IntegerLength[SelectFirst[p5,SequenceCount[ IntegerDigits[ #],PadRight[{},n,x_]]>0&]],{n,12}]] (* _Harvey P. Dale_, Aug 27 2023 *)
%Y A217187 Cf. A215728, A215734.
%K A217187 nonn,base
%O A217187 1,2
%A A217187 _V. Raman_, Sep 27 2012