A075487 Length of iteration list when Collatz-function is iterated with initial value 1+3^n.

2, 3, 7, 19, 111, 22, 96, 33, 76, 75, 43, 135, 134, 133, 132, 144, 205, 129, 190, 140, 95, 94, 261, 428, 91, 258, 394, 331, 255, 254, 390, 389, 388, 462, 461, 460, 459, 458, 457, 456, 455, 454, 453, 501, 500, 450, 498, 497, 752, 495, 494, 493, 748, 491, 746, 489

Offset: 0

Author

Labos Elemer, Sep 26 2002

Keywords

• nonn

Comments

n=2, 1+3^n = 10, list = {10,5,16,8,4,2,1}, so a(2)=7

Links

• T. D. Noe, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A006370, A008908, A074472, A075484-A075488.

Programs

Mathematica

coll[n_]:=Length[NestWhileList[If[EvenQ[#],#/2,3#+1]&,n,#!=1&]]; coll /@ (3^Range[0, 60] + 1) (* Harvey P. Dale, Dec 15 2014 *)

Formula

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