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 A087973 #6 Nov 21 2013 12:48:13
%S A087973 16,52,9232,244,9232,2464,10528,19684,88576,2270104,1008916,1594324,
%T A087973 7174456,65451076,64570084,129140164,1570824736,1961316232,8825923024,
%U A087973 10460353204,47071589416,105911076184,423644304724,66034034786644
%N A087973 Maximal term in Collatz-iteration started at 3^n.
%F A087973 a(n)=A025586[3^n]=A025586[1+3^(n+1)]=A087972[n+1]
%e A087973 Compare to A087972, when iv=1+3^n.
%t A087973 Table[Max[NestList[If[EvenQ[#],#/2,3#+1]&,3^n,100]],{n,25}] (* _Harvey P. Dale_, Dec 08 2011 *)
%Y A087973 Cf. A025586, A087701, A087972.
%K A087973 nonn
%O A087973 1,1
%A A087973 _Labos Elemer_, Sep 24 2003