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 A173479 #9 Jan 16 2017 02:31:14 %S A173479 1,10,300,1000,10000,300000,7000000,10000000,900000000,1000000000,0, %T A173479 300000000000,0,70000000000000,300000000000000,1000000000000000,0, %U A173479 900000000000000000,0,10000000000000000000,0,0,0,300000000000000000000000,1000000000000000000000000,0,0,7000000000000000000000000000,0 %N A173479 a(n) = the smallest n-digit number ending in n-1 zeros that is divisible by n, else 0. %C A173479 See A173478 - A173486. %H A173479 Robert Israel, <a href="/A173479/b173479.txt">Table of n, a(n) for n = 1..999</a> %p A173479 f:= proc(n) local i; for i from 1 to 9 do if i*10^(n-1) mod n = 0 then return i*10^(n-1) fi od: 0 end proc: %p A173479 map(f, [$1..20]); # _Robert Israel_, Jan 16 2017 %K A173479 nonn,base %O A173479 1,2 %A A173479 _Jaroslav Krizek_, Feb 19 2010 %E A173479 a(16)-a(29) from _Robert Israel_, Jan 16 2017