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 A217188 #8 Nov 23 2013 13:52:18
%S A217188 1,4,4,90,176,289,1170,6640,21569,21569,54421
%N A217188 a(n) is the number of digits in the decimal representation of the smallest power of 6 that contains n consecutive identical digits.
%C A217188 Number of digits in 6^k is equal to floor(1 + k*log_10(6)).
%t A217188 k = 0; Join[{1}, Table[While[d = IntegerDigits[6^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 *)
%Y A217188 Cf. A215729, A215735.
%K A217188 nonn,base
%O A217188 1,2
%A A217188 _V. Raman_, Sep 27 2012
%E A217188 a(11) added by _V. Raman_, Nov 23 2013