A075488 Length of iteration list when Collatz-function is iterated with initial value -1+3^n.

2, 4, 11, 10, 97, 96, 33, 32, 44, 43, 135, 134, 133, 132, 100, 99, 191, 190, 140, 139, 262, 261, 428, 427, 395, 394, 331, 330, 391, 390, 389, 388, 462, 461, 460, 459, 458, 457, 456, 455, 454, 453, 501, 500, 499, 498, 497, 496, 495, 494, 493, 492, 747, 746

Offset: 1

Author

Labos Elemer, Sep 26 2002

Keywords

• nonn

Comments

n=3, -1+3^n = 26, list = {26,13,40,20,10,5,16,8,4,2,1}, a(3)=11.

Links

• T. D. Noe, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A006370, A008908, A074472, A075484-A075487.

Programs

Mathematica

lcoll[n_] := Length[NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]]; Table[lcoll[3^i - 1], {i, 54}] (* Jayanta Basu, Jun 15 2013 *)

Formula

a(n) = A008908(3^n-1).