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 A057515 #11 Aug 03 2017 00:42:04 %S A057515 0,1,2,1,3,2,2,1,1,4,3,3,2,2,3,2,2,1,1,2,1,1,1,5,4,4,3,3,4,3,3,2,2,3, %T A057515 2,2,2,4,3,3,2,2,3,2,2,1,1,2,1,1,1,3,2,2,1,1,2,1,1,1,2,1,1,1,1,6,5,5, %U A057515 4,4,5,4,4,3,3,4,3,3,3,5,4,4,3,3,4,3,3,2,2,3,2,2,2,4,3,3,2,2,3,2,2,2,3,2,2 %N A057515 Number of separate "mountains" in mountain ranges encoded by A014486, number of bottom branches (trunks) in the corresponding rooted plane trees, i.e., the degree of the root node. %C A057515 This sequence is produced when the function 'length' (present in programming languages like Lisp, Scheme, Prolog and Haskell) acts on symbolless S-expressions encoded by A014486/A063171. %H A057515 A. Karttunen, <a href="http://www.iki.fi/~kartturi/matikka/Nekomorphisms/gatomorf.htm">Gatomorphisms</a> (Includes the complete Scheme program for computing this sequence) %H A057515 <a href="/index/Li#ListFunsOfLisp">Index entries for the sequences induced by list functions of Lisp</a> %Y A057515 a(n) gives the first digit of A071153(n). %K A057515 nonn %O A057515 0,3 %A A057515 _Antti Karttunen_, Sep 03 2000