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 A173486 #5 Mar 30 2012 19:00:22 %S A173486 900,9000,90000,900000,9000000,90000000,700000000,9000000000, %T A173486 90000000000,900000000000,0,90000000000000,0,7000000000000000, %U A173486 90000000000000000 %N A173486 a(n) = the largest (n+2)-digit number ending in n+1 zeros that is divisible by n, else 0. %C A173486 See A173478 - A173486. %K A173486 nonn,base %O A173486 1,1 %A A173486 _Jaroslav Krizek_, Feb 19 2010