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 A102691 #15 Jul 26 2017 03:12:19 %S A102691 0,4,5,6,7,7,8,8,8,8,9,9,9,9,9,9,9,9,9,9,9 %N A102691 Least n-expodigital number (i.e., numbers m such that m^n has exactly n decimal digits). %C A102691 10^(n-1) being the smallest n-digit number, n-expodigital numbers exist iff 10^(n-1) < 9^n, i.e., iff n-1 < n*log_10(9); this condition holds for all n up to 21 because beyond we have, for instance, 20 < 22*log_10(9) < 21. Thus numbers can be at most 21-expodigital. %F A102691 a(n) = 10 - A102690(n). %e A102691 a(3)=5 because this is the first number followed by 6,7,8 and 9 which are all 3-expodigital: 5^3 = 125; 6^3 = 216; 7^3 = 343; 8^3 = 512; 9^3 = 729. %Y A102691 Cf. A102690. %Y A102691 Essentially the same as A067471. - _R. J. Mathar_, Aug 30 2008 %K A102691 fini,full,nonn,base %O A102691 1,2 %A A102691 _Lekraj Beedassy_, Jan 21 2005 %E A102691 Edited by _Charles R Greathouse IV_, Aug 03 2010