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 A183234 #8 Mar 30 2012 18:57:12
%S A183234 2,5,8,9,12,14,17,20,23,26,27,30,33,35,38,41,44,47,50,53,54,57,60,63,
%T A183234 64,65,68,71,74,75,77,80,83,86,87,90,93,96,99,100,103,104,107,110,113,
%U A183234 114,117,119,122,125,128,129,132,134,135,138,141,144,145,148,150,152,155,158,161,162,165,167,170,173,176,179,180,183,185,188,189,192,195,198,199
%N A183234 Ordering of the numbers in tree A183232; complement of A183233.
%F A183234 The monotonic ordering of the numbers in the set S generated by these rules: 2 is in S, and if n is in S, then (n^2+5n+2)/2 and n+Floor(1/2+sqrt(2n+4)) are in S.
%t A183234 nn=200; t={2}; t0=t; While[t=Select[Union[t,(1/2)*(t^2+5t+2), t+Floor[1/2+(2t+4)^(1/2)]],#<=nn&]; t0 !t, t0=t]; t
%t A183234 f[s_List] := Select[ Union@ Join[s, (s^2 + 5 s + 2)/2, s + Floor[1/2 + Sqrt@ (2 s + 4)]], # < 201 &]; NestWhile[f, {2}, UnsameQ, All]
%Y A183234 Cf. A183232, A183233.
%K A183234 nonn
%O A183234 1,1
%A A183234 _Clark Kimberling_, Jan 02 2011