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 A269864 #9 Dec 13 2023 08:21:15 %S A269864 1,2,3,4,5,6,9,10,7,8,15,16,11,26,27,28,13,12,21,22,25,36,45,46,19,14, %T A269864 33,76,65,66,81,82,31,18,39,34,17,56,63,64,29,50,75,106,41,116,135, %U A269864 136,53,24,57,40,35,86,99,226,143,120,195,196,71,206,243,244,89,38,93,52,23,96,117,100,77,20,51,166,145,156,189,190,119,32,87 %N A269864 Permutation of natural numbers: a(1) = 1, a(2n) = A269360(a(n)), a(2n+1) = A250469(1+a(n)). %C A269864 This sequence can be represented as a binary tree. When the parent contains n, the left hand child contains A269360(n) [= 1+A250469(n)] and the right hand child contains A250469(1+n): %C A269864 1 %C A269864 | %C A269864 ................../ \.................. %C A269864 2 3 %C A269864 4......../ \........5 6......../ \........9 %C A269864 / \ / \ / \ / \ %C A269864 / \ / \ / \ / \ %C A269864 / \ / \ / \ / \ %C A269864 10 7 8 15 16 11 26 27 %C A269864 28 13 12 21 22 25 36 45 46 19 14 33 76 65 66 81 %C A269864 etc. %H A269864 Antti Karttunen, <a href="/A269864/b269864.txt">Table of n, a(n) for n = 1..5887</a> %H A269864 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A269864 a(1) = 1, a(2n) = 1 + A250469(a(n)), a(2n+1) = A250469(1+a(n)). %o A269864 (Scheme, with memoization-macro definec) %o A269864 (definec (A269864 n) (cond ((= 1 n) 1) ((even? n) (+ 1 (A250469 (A269864 (/ n 2))))) (else (A250469 (+ 1 (A269864 (/ (- n 1) 2))))))) %Y A269864 Inverse: A269863. %Y A269864 Cf. A250469, A269360. %Y A269864 Cf. also A269865, A269866, A269867. %Y A269864 Differs from similarly constructed A245606 for the first time at n=15, where a(15)=27 instead of 21. %K A269864 nonn,tabf %O A269864 1,2 %A A269864 _Antti Karttunen_, Mar 13 2016