A143812 Maximal number of halving and tripling steps to reach 1 in '3x+1' problem for range (1, ..., n).

1, 2, 8, 8, 8, 9, 17, 17, 20, 20, 20, 20, 20, 20, 20, 20, 20, 21, 21, 21, 21, 21, 21, 21, 24, 24, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 112, 113, 113, 113, 113, 113

Offset: 1

Author

Benjamin Frost (benjamin.frost(AT)students.adelaide.edu.au), Sep 02 2008

Keywords

• nonn

Links

• Index entries for sequences related to 3x+1 (or Collatz) problem

Crossrefs

Cf. A006877, A033492.

Programs

Mathematica

nst[n_]:=Length[NestWhileList[If[EvenQ[#],#/2,3#+1]&,n,#>1&]]; nn=60; With[ {stps= Array[nst,nn]},Table[Max[Take[stps,n]],{n,nn}]]  (* Harvey P. Dale, Apr 17 2014 *)

Extensions

Corrected and extended by Harvey P. Dale, Apr 17 2014