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 A075176 #2 May 01 2014 02:44:55 %S A075176 1,2,3,6,0,4,0,12,5,10,15,30,0,20,0,60,0,0,9,18,0,0,0,36,0,0,45,90,0, %T A075176 0,0,180,0,0,0,0,0,8,0,24,0,0,0,0,0,40,0,120,0,0,0,0,0,0,0,72,0,0,0,0, %U A075176 0,0,0,360,7,14,21,42,0,28,0,84,35,70,105,210,0,140,0,420,0,0,63,126,0,0 %N A075176 Inverse function of N -> N injection A075175. %C A075176 a(n) = 0 for those n which do not occur as the values of A075175. All positive natural numbers occur here once. %Y A075176 a(A075175(n)) = n for all n >= 1. Differs from A075174 for first time at a(18) = 9, while A075174(18) = 0. %K A075176 nonn %O A075176 0,2 %A A075176 _Antti Karttunen_, Sep 13 2002