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 A173480 #2 Mar 30 2012 19:00:22 %S A173480 9,90,900,9000,90000,900000,7000000,90000000,900000000,90000000000,0, %T A173480 900000000000,0,70000000000000,900000000000000 %N A173480 a(n) = the largest n-digit number ending in n-1 zeros that is divisible by n, else 0. %C A173480 See A173478 - A173486. %K A173480 nonn,base %O A173480 1,1 %A A173480 _Jaroslav Krizek_, Feb 19 2010