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 A072758 #3 Mar 30 2012 18:57:04 %S A072758 0,1,2,3,4,6,5,7,8,12,9,13,10,15,11,16,14,21,17,25,18,27,19,28,20,30, %T A072758 22,33,23,34,24,36,26,39,29,43,31,46,32,48,35,52,37,55,38,57,40,60,41, %U A072758 61,42,63,44,66,45,67,47,70,49,73,50,75,51,76,53,79,54,81,56,84,58,87 %N A072758 a(0)=0, a(1)=1 and for k>1, a(2k)=least positive integer not a(j) for j<2k; and a(2k+1)=a(2k)+Floor(a(2k)/2). %C A072758 A permutation of the nonnegative integers; a(2n)=A072756(n+1), a(2n+1)=A072757(n-1) for n>=1. %Y A072758 Cf. A072756, A072757, A072759. %K A072758 nonn %O A072758 0,3 %A A072758 _Clark Kimberling_, Jul 09 2002