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

1,1

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

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 *)

Prog

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

Crossrefs

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

Sequence in context: A057404 A173713 A252485 * A093159 A350453 A374988

Adjacent sequences: A185586 A185587 A185588 * A185590 A185591 A185592

Keyword

nonn

Author

N. J. A. Sloane, Feb 04 2011

Status

approved