A185589 Iterate the map in A006369 starting at 144.

144, 96, 64, 85, 113, 151, 201, 134, 179, 239, 319, 425, 567, 378, 252, 168, 112, 149, 199, 265, 353, 471, 314, 419, 559, 745, 993, 662, 883, 1177, 1569, 1046, 1395, 930, 620, 827, 1103, 1471, 1961, 2615, 3487, 4649, 6199, 8265, 5510, 7347, 4898, 6531, 4354, 5805, 3870, 2580, 1720, 2293, 3057, 2038, 2717, 3623, 4831

Offset: 1

Author

N. J. A. Sloane, Feb 04 2011

Keywords

• nonn

Comments

Lagarias, page 270, appears to imply that this trajectory has period 12 and smallest element 144, which is not true.

References

• J. C. Lagarias, ed., The Ultimate Challenge: The 3x+1 Problem, Amer. Math. Soc., 2010; see page 270.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to 3x+1 (or Collatz) problem

Crossrefs

Cf. A028394, A028396, A094328, A094329, A185590.

Programs

Haskell

a185589 n = a185589_list !! (n-1)
a185589_list = iterate a006369 144  -- Reinhard Zumkeller, Dec 31 2011

Mathematica

f[n_] := If[Mod[n, 3] == 0, 2*n/3, Round[4*n/3]]; a[1] = 144; a[n_] := a[n] = f[a[n - 1]]; Table[a[n], {n, 1, 59}]  (* Jean-François Alcover, Jun 10 2013 *)
SubstitutionSystem[{n_ :> Switch[Mod[n, 3], 0, 2n/3, 1, (4n - 1)/3, , (4n + 1)/3]}, {144}, 60] // Flatten (* _Jean-François Alcover, Mar 01 2019 *)