A087254 If we start the Collatz-iteration at these values, each divisible by 4, all subsequent terms in trajectory are smaller than the initial value.

4, 8, 20, 24, 32, 48, 56, 68, 72, 80, 84, 96, 104, 116, 128, 132, 144, 152, 168, 176, 180, 192, 200, 212, 224, 228, 240, 260, 264, 272, 276, 288, 296, 308, 312, 320, 324, 336, 344, 356, 360, 368, 372, 384, 392, 404, 408, 416, 452, 456, 464, 468, 480, 488, 512

Offset

1,1

Comments

Numbers that are not highest in any Collatz trajectory other than n. - Jayanta Basu, May 27 2013

Links

Table of n, a(n) for n=1..55.

Example

n=104: iteration list = {104,52,26,13,40,20,10,5,16,8,4,2,1}, where initial-value = largest-term.

Mathematica

mcoll[n_]:=Max@@NestWhileList[If[EvenQ[#], #/2, 3#+1] &, n, #>1 &]; t={}; Do[c=i=0; While[c!=1 && ++i<n, If[mcoll[i]==n, c=1]]; If[c==0 && mcoll[n]==n, AppendTo[t, n]], {n, 4, 512, 4}]; t (* Jayanta Basu, May 27 2013 *)

Crossrefs

Cf. A025586, A087251-A087253, A222562 (with 1 and 2 prepended).

Sequence in context: A178447 A006580 A061814 * A160726 A191483 A062717

Adjacent sequences: A087251 A087252 A087253 * A087255 A087256 A087257

Keyword

nonn

Author

Labos Elemer, Sep 08 2003

Status

approved