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 A220263 #9 Jul 13 2013 12:04:34
%S A220263 1,2,8,9,17,20,10,18,21,21,8,11,24,112,19,27,22,22,35,9,30,17,12,25,
%T A220263 113,113,33,20,108,28,15,23,116,15,36,36,23,10,31,18,18,13,119,26,26,
%U A220263 39,114,114,70,34,34,21,21,47,109,47,122,29,29,42,16,16,24
%N A220263 Lengths of Collatz trajectories starting with terms of A177729.
%C A220263 Row lengths in A192719.
%H A220263 Reinhard Zumkeller, <a href="/A220263/b220263.txt">Table of n, a(n) for n = 1..10000</a>
%t A220263 coll[n_]:=NestWhileList[If[EvenQ[#],#/2,3#+1]&,n,#>1&]; t={1}; Do[If[FreeQ[Union@@Table[coll[i],{i,n-1}],n],AppendTo[t,Length[coll[n]]]],{n,2,144}]; t (* _Jayanta Basu_, May 29 2013 *)
%o A220263 (Haskell)
%o A220263 a220263 = length . a192719_row
%Y A220263 Cf. A006577.
%K A220263 nonn
%O A220263 1,2
%A A220263 _Reinhard Zumkeller_, Jan 03 2013