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 A270202 #9 Mar 25 2016 07:48:02 %S A270202 1,2,9,3,11,12,36,4,15,14,39,17,40,52,108,5,16,22,51,20,47,59,114,25, %T A270202 55,60,118,77,167,156,312,6,18,24,54,30,73,75,165,28,67,68,139,85,185, %U A270202 166,339,34,84,80,174,87,187,173,347,117,227,254,496,236,461,475,852,7,21,26,56,33,76,79,170,43,99,112,216,115,219,251,490,41 %N A270202 Permutation of natural numbers: a(1) = 1, a(2n) = A270189(1+a(n)), a(2n+1) = A270190(a(n)). %C A270202 This sequence can be represented as a binary tree. Each left hand child is produced as A270189(1+n), and each right hand child as A270190(n), when the parent node contains n: %C A270202 1 %C A270202 ................../ \.................. %C A270202 2 9 %C A270202 3......../ \........11 12......../ \........36 %C A270202 / \ / \ / \ / \ %C A270202 / \ / \ / \ / \ %C A270202 / \ / \ / \ / \ %C A270202 4 15 14 39 17 40 52 108 %C A270202 5 16 22 51 20 47 59 114 25 55 60 118 77 167 156 312 %C A270202 etc. %H A270202 Antti Karttunen, <a href="/A270202/b270202.txt">Table of n, a(n) for n = 1..8192</a> %H A270202 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A270202 a(1) = 1, a(2n) = A270189(1+a(n)), a(2n+1) = A270190(a(n)). %o A270202 (Scheme, with memoization-macro definec) %o A270202 (definec (A270202 n) (cond ((= 1 n) n) ((even? n) (A270189 (+ 1 (A270202 (/ n 2))))) (else (A270190 (A270202 (/ (- n 1) 2)))))) %Y A270202 Inverse: A270201. %Y A270202 Cf. A270189, A270190. %Y A270202 Similar permutation: A270194. %K A270202 nonn,tabf %O A270202 1,2 %A A270202 _Antti Karttunen_, Mar 16 2016