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 A253893 #11 Jan 25 2015 23:22:32 %S A253893 0,1,1,2,2,2,3,2,3,4,3,4,3,3,4,4,3,3,4,4,5,5,3,5,4,4,5,4,5,5,5,4,5,5, %T A253893 5,6,6,4,5,6,4,6,5,5,6,5,5,5,6,4,6,6,4,6,6,5,6,5,5,6,5,6,4,6,6,6,6,4, %U A253893 7,7,6,6,6,5,7,7,5,6,7,6,6,7,5,7,6,6,7,5,6,7,7,6,6,6,5,7,7,6,7,7,6,6,6,6,6,7,7,6,7,7,7,7,5,7,7,6,7,7,7,7,7,5 %N A253893 a(1) = 0, for n > 1, a(n) = 1 + a(A253889(n)). %C A253893 When A048673 is represented as a binary tree, then a(n) gives the distance of node containing n from 1 at top. %H A253893 Antti Karttunen, <a href="/A253893/b253893.txt">Table of n, a(n) for n = 1..8192</a> %F A253893 a(1) = 0, for n > 1, a(n) = 1 + A253893(A253889(n)). %F A253893 a(n) = A000523(A064216(n)). %F A253893 a(n) = A253894(n) - 1. %F A253893 Other identities: %F A253893 a(A007051(n)) = n for all n >= 0. %o A253893 (Scheme, with memoization-macro definec) %o A253893 (definec (A253893 n) (if (= 1 n) 0 (+ 1 (A253893 (A253889 n))))) %Y A253893 One less than A253894. %Y A253893 Cf. A000523, A007051, A064216, A253786, A253887, A253889. %K A253893 nonn %O A253893 1,4 %A A253893 _Antti Karttunen_, Jan 22 2015