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 A268712 #6 Feb 13 2016 23:17:58 %S A268712 1,2,3,6,4,9,5,13,11,10,7,21,18,12,8,29,23,25,20,24,19,14,15,45,40,39, %T A268712 34,28,22,17,16,62,56,49,42,54,48,44,37,51,47,43,36,30,26,33,27,95,87, %U A268712 84,75,80,74,73,65,61,53,46,41,38,32,35,31,129,120,115,108,100,93,88,82,112,105,99,92,94,86,78,70 %N A268712 Permutation of natural numbers: a(1) = 1, a(2n) = A268677(a(n)), a(2n+1) = A268678(1+a(n)). %C A268712 This sequence can be represented as a binary tree. Each left hand child is produced as A268677(n), and each right hand child as A268678(1+n), when the parent node contains n: %C A268712 | %C A268712 ...................1................... %C A268712 2 3 %C A268712 6......../ \........4 9......../ \........5 %C A268712 / \ / \ / \ / \ %C A268712 / \ / \ / \ / \ %C A268712 / \ / \ / \ / \ %C A268712 13 11 10 7 21 18 12 8 %C A268712 29 23 25 20 24 19 14 15 45 40 39 34 28 22 17 16 %C A268712 etc. %H A268712 Antti Karttunen, <a href="/A268712/b268712.txt">Table of n, a(n) for n = 1..16383</a> %H A268712 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A268712 a(1) = 1, after which: a(2n) = A268677(a(n)), a(2n+1) = A268678(1+a(n)). %o A268712 (Scheme, with memoization-macro definec) %o A268712 (definec (A268712 n) (cond ((= 1 n) n) ((even? n) (A268677 (A268712 (/ n 2)))) (else (A268678 (+ 1 (A268712 (/ (- n 1) 2))))))) %Y A268712 Inverse: A268711. %Y A268712 Cf. A268677, A268678. %K A268712 nonn,tabf %O A268712 1,2 %A A268712 _Antti Karttunen_, Feb 11 2016