A087253 Number of distinct initial values of various 3x+1 trajectories of which the peak-value equals 4n.

1, 1, 0, 6, 1, 1, 0, 1, 0, 3, 0, 1, 12, 1, 0, 3, 1, 1, 0, 1, 1, 8, 0, 1, 3, 1, 0, 3, 1, 0, 0, 1, 1, 3, 0, 1, 3, 1, 0, 13, 0, 1, 0, 1, 1, 3, 0, 1, 8, 1, 0, 3, 1, 0, 0, 1, 1, 6, 0, 1, 3, 0, 0, 3, 1, 1, 0, 1, 1, 3, 0, 1, 0, 1, 0, 14, 1, 1, 0, 1, 1, 0, 0, 1, 6, 1, 0, 3, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 3, 1, 1, 0, 1, 0

Offset

1,4

Links

Table of n, a(n) for n=1..105.

Example

n=13: a(13)=12 because peak=4.13=52
occurs at the following 12 initial values:
{7,9,11,14,17,18,22,28,34,36,44,52};
this list differs from trajectory started at iv=52.
Impossible peaks of 4k form are listed in A087252
(corresponding to a[x]=0).

Crossrefs

Cf. A025586.

Sequence in context: A114153 A119832 A166141 * A197686 A331277 A369458

Adjacent sequences: A087250 A087251 A087252 * A087254 A087255 A087256

Keyword

nonn

Author

Labos Elemer, Sep 08 2003

Status

approved