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 A185590 #24 Oct 18 2024 20:31:21
%S A185590 44,59,79,105,70,93,62,83,111,74,99,66,44,59,79,105,70,93,62,83,111,
%T A185590 74,99,66,44,59,79,105,70,93,62,83,111,74,99,66,44,59,79,105,70,93,62,
%U A185590 83,111,74,99,66,44,59,79,105,70,93,62,83,111,74,99,66,44,59,79,105,70,93,62,83,111,74,99,66,44
%N A185590 Iterate the map in A006369 starting at 44.
%C A185590 Periodic with period length 12.
%D A185590 A. O. L. Atkin, Comment on Problem 63-13, SIAM Rev., 8 (1966), 234-236.
%D A185590 J. C. Lagarias, ed., The Ultimate Challenge: The 3x+1 Problem, Amer. Math. Soc., 2010; see page 270. (beware of typo: Lagarias says the orbit of 144 (not 44) has period 12.)
%H A185590 Reinhard Zumkeller, <a href="/A185590/b185590.txt">Table of n, a(n) for n = 1..10000</a>
%H A185590 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%t A185590 f[n_] := If[Mod[n, 3] == 0, 2*n/3, Round[4*n/3]]; a[1] = 44; a[n_] := a[n] = f[a[n - 1]]; Table[a[n], {n, 1, 73}] (* _Jean-François Alcover_, Jun 10 2013 *)
%o A185590 (Haskell)
%o A185590 a185590 n = a185590_list !! (n-1)
%o A185590 a185590_list = iterate a006369 44 -- _Reinhard Zumkeller_, Dec 31 2011
%Y A185590 Cf. A006369, A028394, A028396, A094328, A094329, A185589.
%Y A185590 Trajectories under A006368 and A006369: A180853, A217218, A185590, A180864, A028393, A028394, A094328, A094329, A028396, A028395, A217729, A182205, A223083-A223088, A185589, A185590.
%K A185590 nonn,easy
%O A185590 1,1
%A A185590 _N. J. A. Sloane_, Feb 04 2011