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 A266418 #7 Jan 30 2016 03:10:37 %S A266418 1,4,2,10,6,7,3,22,20,15,11,16,12,9,5,40,53,37,45,29,33,24,21,31,35, %T A266418 25,23,19,18,13,8,68,111,85,156,64,104,75,123,51,74,56,87,43,59,39,48, %U A266418 54,80,61,90,46,60,42,57,36,44,34,41,27,26,17,14,107,210,167,387,133,276,229,573,101,198,158,351,120 %N A266418 Permutation of natural numbers: a(1) = 1, a(2n) = A266410(a(n)), a(2n+1) = A266409(1+a(n)). %C A266418 This sequence can be represented as a binary tree. Each left hand child is produced as A266410(n), and each right hand child as A266409(1+n), when the parent node contains n: %C A266418 | %C A266418 ...................1................... %C A266418 4 2 %C A266418 10......../ \........6 7......../ \........3 %C A266418 / \ / \ / \ / \ %C A266418 / \ / \ / \ / \ %C A266418 / \ / \ / \ / \ %C A266418 22 20 15 11 16 12 9 5 %C A266418 40 53 37 45 29 33 24 21 31 35 25 23 19 18 13 8 %C A266418 etc. %H A266418 Antti Karttunen, <a href="/A266418/b266418.txt">Table of n, a(n) for n = 1..4095</a> %H A266418 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A266418 a(1) = 1, after which: a(2n) = A266410(a(n)), a(2n+1) = A266409(1+a(n)). %F A266418 As a composition of related permutations: %F A266418 a(n) = A266638(A237126(n)). %o A266418 (Scheme, with memoization-macro definec) %o A266418 (definec (A266418 n) (cond ((<= n 1) n) ((even? n) (A266410 (A266418 (/ n 2)))) (else (A266409 (+ 1 (A266418 (/ (- n 1) 2))))))) %Y A266418 Inverse: A266417. %Y A266418 Cf. A266409, A266410. %Y A266418 Similar or related permutations: A237126, A266638. %K A266418 nonn,tabf %O A266418 1,2 %A A266418 _Antti Karttunen_, Jan 28 2016