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 A161021 #15 Oct 13 2022 14:31:05 %S A161021 703,2110,1055,3166,1583,4750,2375,7126,3563,10690,5345,16036,8018, %T A161021 4009,12028,6014,3007,9022,4511,13534,6767,20302,10151,30454,15227, %U A161021 45682,22841,68524,34262,17131,51394,25697,77092,38546,19273,57820,28910 %N A161021 Collatz (or 3x+1) trajectory starting at 703. %C A161021 703 = A060412(5); a(A006577(703)) = a(170) = 1; %C A161021 a(n) = A008884(n-59) for n with 162 <= n <= 170; %C A161021 a(n) = A161022(n+53) for n with 155 <= n <= 170; %C A161021 a(n) = A161023(n+153) for n with 144 <= n <= 170. %H A161021 R. Zumkeller, <a href="/A161021/b161021.txt">Table of n, a(n) for n = 0..170</a> %H A161021 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a> %H A161021 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,1). %t A161021 NestList[If[EvenQ[#],#/2,3#+1]&,703,40] (* _Harvey P. Dale_, Nov 27 2011 *) %K A161021 nonn,easy %O A161021 0,1 %A A161021 _Reinhard Zumkeller_, Jun 03 2009 %E A161021 Edited by _N. J. A. Sloane_, Jul 27 2019