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 A087701 #11 Jul 19 2019 12:26:28
%S A087701 1,16,52,160,9232,9232,4372,13120,39364,118096,1276936,1276936,
%T A087701 6810136,9565936,28697812,86093440,1570824736,1570824736,2324522932,
%U A087701 6973568800,20920706404,62762119216,188286357652,564859072960,9161049517720
%N A087701 Maximal term in Collatz-iteration started at -1+2^n.
%F A087701 a(n) = A025586(2^n-1).
%t A087701 Table[Max[NestWhileList[If[EvenQ[#],#/2,3#+1]&,2^n-1,#>1&]],{n,30}] (* _Harvey P. Dale_, Jul 19 2019 *)
%Y A087701 Cf. A025586.
%K A087701 nonn
%O A087701 1,2
%A A087701 _Labos Elemer_, Sep 24 2003