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 A205591 #11 Jul 09 2015 15:15:18 %S A205591 1,2,3,4,6,7,8,12,13,14,16,20,24,26,27,28,32,36,40,48,50,52,54,55,56, %T A205591 64,68,72,80,88,96,100,102,104,108,109,110,112,120,128,136,140,144, %U A205591 160,168,176,192,196,200,204,206,208,216,217,218,220,222,224,240,248,256 %N A205591 a(1) = 1, a(n) = a(floor((2n-1)/3)) + a(floor(2n/3)) for n > 1. %C A205591 In other words, a(1)=1 and then any term is a sum of two earliest possible previous terms (not necessarily distinct), given that each term must be used in summation no more than three times. So a(2)=1+1 (thus 1 gets used twice), a(3)=1+2 (thus 1 gets used for the third and final time, then 2 steps in), and so on. - _Ivan Neretin_, Jul 09 2015 %H A205591 Joseph Myers, <a href="/A205591/b205591.txt">Table of n, a(n) for n = 1..1000</a> %H A205591 <a href="http://www.bmoc.maths.org/home/bmo2-2012.pdf">2011/12 British Mathematical Olympiad Round 2</a>, Problem 2. %Y A205591 Cf. A205592, A205593, A205594, A205595, A205596. %K A205591 easy,nonn %O A205591 1,2 %A A205591 _Joseph Myers_, Jan 29 2012