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 A126307 #7 Jul 22 2017 08:32:36 %S A126307 0,1,1,2,1,1,2,2,3,1,1,1,1,1,2,2,2,2,2,3,3,3,4,1,1,1,1,1,1,1,1,1,1,1, %T A126307 1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3,4,4,4,4,5,1,1,1, %U A126307 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 %N A126307 a(n) is the length of the leftmost ascent (i.e., height of the first peak) in the n-th Dyck path encoded by A014486(n). %C A126307 In other words, this sequence gives the number of leading 1's in the terms of A063171. %F A126307 a(n) = A090996(A014486(n)). %e A126307 A014486(20) = 228 (11100100 in binary), encodes the following Dyck path: %e A126307 /\ %e A126307 / \/\ %e A126307 / \ %e A126307 and the first rising (left-hand side) slope has length 3, thus a(20)=3. %Y A126307 a(n) = A099563(A071156(n)) = A057515(A125985(n)) = A080237(A057164(n)) = A057515(A057504(A057164(n))). %K A126307 nonn %O A126307 0,4 %A A126307 _Antti Karttunen_, Jan 02 2007