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 A198588 #10 Mar 30 2012 17:23:02
%S A198588 11,23,45,93,181,201,369,373,401,403,725,739,753,803,805,1477,1493,
%T A198588 1507,1605,1611,1613,2901,2957,3013,3033,3213,3221,3223,5909,5973,
%U A198588 6029,6065,6067,6421,6445,6453,6465,11605,11829,12053,12131,12133,12853,12885,12893
%N A198588 Odd numbers producing 5 odd numbers in the Collatz iteration.
%H A198588 Vincenzo Librandi and T. D. Noe, <a href="/A198588/b198588.txt">Table of n, a(n) for n = 1..900</a> (terms 1 to 128 from Vincenzo Librandi)
%t A198588 Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; t = {}; Do[If[Length[Select[Collatz[n], OddQ]] == 5, AppendTo[t, n]], {n, 1, 20000, 2}]; t
%Y A198588 Cf. A198584.
%K A198588 nonn
%O A198588 1,1
%A A198588 _T. D. Noe_, Oct 31 2011