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 A075487 #7 Dec 15 2014 14:58:54
%S A075487 2,3,7,19,111,22,96,33,76,75,43,135,134,133,132,144,205,129,190,140,
%T A075487 95,94,261,428,91,258,394,331,255,254,390,389,388,462,461,460,459,458,
%U A075487 457,456,455,454,453,501,500,450,498,497,752,495,494,493,748,491,746,489
%N A075487 Length of iteration list when Collatz-function is iterated with initial value 1+3^n.
%C A075487 n=2, 1+3^n = 10, list = {10,5,16,8,4,2,1}, so a(2)=7
%H A075487 T. D. Noe, <a href="/A075487/b075487.txt">Table of n, a(n) for n = 0..1000</a>
%F A075487 a(n) = A008908(3^n+1).
%t A075487 coll[n_]:=Length[NestWhileList[If[EvenQ[#],#/2,3#+1]&,n,#!=1&]]; coll /@ (3^Range[0, 60] + 1) (* _Harvey P. Dale_, Dec 15 2014 *)
%Y A075487 Cf. A006370, A008908, A074472, A075484-A075488.
%K A075487 nonn
%O A075487 0,1
%A A075487 _Labos Elemer_, Sep 26 2002