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 A094329 #17 Mar 01 2019 08:04:41
%S A094329 16,21,14,19,25,33,22,29,39,26,35,47,63,42,28,37,49,65,87,58,77,103,
%T A094329 137,183,122,163,217,289,385,513,342,228,152,203,271,361,481,641,855,
%U A094329 570,380,507,338,451,601,801,534,356,475,633,422,563,751,1001,1335,890,1187,1583
%N A094329 Iterate the map in A006369 starting at 16.
%D A094329 J. C. Lagarias, ed., The Ultimate Challenge: The 3x+1 Problem, Amer. Math. Soc., 2010; see page 270.
%H A094329 T. D. Noe, <a href="/A094329/b094329.txt">Table of n, a(n) for n=1..1001</a>
%H A094329 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%t A094329 SubstitutionSystem[{n_ :> Switch[Mod[n, 3], 0, 2n/3, 1, (4n - 1)/3, _, (4n + 1)/3]}, {16}, 60] // Flatten (* _Jean-François Alcover_, Mar 01 2019 *)
%o A094329 (Haskell)
%o A094329 a094329 n = a094329_list !! (n-1)
%o A094329 a094329_list = iterate a006369 16 -- _Reinhard Zumkeller_, Dec 31 2011
%Y A094329 See A006368, A028394, A028396, A094328, A185589, A185590.
%K A094329 nonn
%O A094329 1,1
%A A094329 _N. J. A. Sloane_, Jun 04 2004