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 A177001 #5 Jul 29 2013 00:50:36
%S A177001 0,0,0,0,1,1,2,2,2,2,2,3,3,4,4,5,5,5,6,6,6,6,7,7,7,8,8,8,9,9,9,10,10,
%T A177001 11,11,11,11,12,12,12,13,13,13,14,14,15,15,15,16,16,16,17,17,18,18,18,
%U A177001 18,19,19,20,20,20,21,21,22,22,23,23,24,24,24,24,25,25,25,26,26,27,27,28
%N A177001 The number of 3x+1 steps in the Collatz iteration of A033491(n), the least number requiring n iterations.
%C A177001 It appears that a(n) is the maximum number of 3x+1 steps for all numbers requiring n Collatz iterations, which is row n of A127824.
%F A177001 For large n, a(n) ~ n * log(2)/log(6).
%e A177001 24 is the smallest number that requires 10 Collatz iterations. The iteration uses two 3x+1 steps to produce 24, 12, 6, 3, 10, 5, 16, 8, 4, 2, 1. Hence a(10)=2.
%t A177001 col[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; Table[k = 1; While[Length[(y = col[k])] - 1 != n, k++]; Count[y, _?OddQ] - 1, {n, 80}] (* _Jayanta Basu_, Jul 27 2013 *)
%K A177001 nonn
%O A177001 1,7
%A A177001 _T. D. Noe_, Apr 30 2010