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 A075172 #2 May 01 2014 02:44:55 %S A075172 0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,3,4,5,5,5,5,5,5,5,5,5,5,5,5,5,4,4,5,5, %T A075172 6,6,6,6,6,6,6,6,6,6,6,6,6,5,5,6,6,6,6,6,6,6,6,6,6,6,5,5,5,4,5,6,6,6, %U A075172 7,7,7,7,7,7,7,7,7,7,7,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,6,6,6,6,7,7,7,7,7,7,7 %N A075172 Number of edges in each rooted plane tree produced with the binary run length unranking algorithm presented in A075171. %C A075172 Also the digital length of A075171(n)/ 2. Each value v occurs A000108(v) times. %Y A075172 Permutation of A072643. %K A075172 nonn %O A075172 0,3 %A A075172 _Antti Karttunen_, Sep 13 2002