A185590 - OEIS

%I #24 Oct 18 2024 20:31:21

%S 44,59,79,105,70,93,62,83,111,74,99,66,44,59,79,105,70,93,62,83,111,

%T 74,99,66,44,59,79,105,70,93,62,83,111,74,99,66,44,59,79,105,70,93,62,

%U 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 Iterate the map in A006369 starting at 44.

%C Periodic with period length 12.

%D A. O. L. Atkin, Comment on Problem 63-13, SIAM Rev., 8 (1966), 234-236.

%D 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 Reinhard Zumkeller, <a href="/A185590/b185590.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>

%t 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 (Haskell)

%o a185590 n = a185590_list !! (n-1)

%o a185590_list = iterate a006369 44  -- _Reinhard Zumkeller_, Dec 31 2011

%Y Cf. A006369, A028394, A028396, A094328, A094329, A185589.

%Y Trajectories under A006368 and A006369: A180853, A217218, A185590, A180864, A028393, A028394, A094328, A094329, A028396, A028395, A217729, A182205, A223083-A223088, A185589, A185590.

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_, Feb 04 2011