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 A265339 #12 Aug 12 2019 22:37:57 %S A265339 0,0,1,1,2,3,3,2,4,4,7,9,6,6,19,10,8,12,9,7,10,5,5,19,12,8,13,13,22, %T A265339 27,21,18,64,28,23,36,18,21,55,11,20,57,57,24,58,37,25,30,24,15,73,31, %U A265339 26,39,27,22,28,16,11,64,30,23,31,14,16,55,15,20,46,46,17,58,36,25,37,17,14,73,39,26,40,40 %N A265339 a(n) = A263273(A004526(A263273(n))). %C A265339 When permutation A263273 is viewed as a binary tree, a(n) gives the parent node of node containing n, for all n >= 1. %C A265339 Each n occurs exactly twice in the sequence. %H A265339 Antti Karttunen, <a href="/A265339/b265339.txt">Table of n, a(n) for n = 0..16384</a> %F A265339 a(n) = A263273(A004526(A263273(n))). %o A265339 (Scheme) (define (A265339 n) (A263273 (A004526 (A263273 n)))) %Y A265339 Cf. A004526, A263273, A265340. %K A265339 nonn,base,look %O A265339 0,5 %A A265339 _Antti Karttunen_, Dec 18 2015