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 A273666 #11 May 30 2016 18:25:05 %S A273666 0,1,2,3,6,4,8,5,24,10,12,7,30,13,14,9,120,34,36,16,48,18,26,11,144, %T A273666 42,50,19,54,20,32,15,720,154,156,46,168,49,60,22,240,66,72,25,126,37, %U A273666 38,17,840,186,192,58,246,68,74,27,264,73,78,28,150,44,56,21,5040,874,876,199,888,202,204,64,960,216,242,67,288,82,84,31 %N A273666 Permutation of nonnegative integers: a(0) = 0; after which, a(2n) = A153880(a(n)), a(2n+1) = A273670(a(n)). %C A273666 This sequence can be represented as a binary tree. Each left hand child is produced as A153880(n), and each right hand child as A273670(n), when their parent contains n >= 1: %C A273666 0 %C A273666 | %C A273666 ...................1................... %C A273666 2 3 %C A273666 6......../ \........4 8......../ \........5 %C A273666 / \ / \ / \ / \ %C A273666 / \ / \ / \ / \ %C A273666 / \ / \ / \ / \ %C A273666 24 10 12 7 30 13 14 9 %C A273666 120 34 36 16 48 18 26 11 144 42 50 19 54 20 32 15 %C A273666 etc. %H A273666 Antti Karttunen, <a href="/A273666/b273666.txt">Table of n, a(n) for n = 0..1023</a> %H A273666 <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a> %H A273666 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A273666 a(0) = 0; after which, a(2n) = A153880(a(n)), a(2n+1) = A273670(a(n)). %o A273666 (Scheme, with memoization-macro definec) %o A273666 (definec (A273666 n) (cond ((zero? n) n) ((even? n) (A153880 (A273666 (/ n 2)))) (else (A273670 (A273666 (/ (- n 1) 2)))))) %Y A273666 Inverse: A273665. %Y A273666 Cf. A153880, A273670. %Y A273666 Related or similar permutations: A255566, A273668. %K A273666 nonn,base,tabf %O A273666 0,3 %A A273666 _Antti Karttunen_, May 30 2016