A095383 Number of different initial values for 3x+1 trajectories started with initial values not exceeding 2^n and in which the peak values are larger than 2^n.

0, 1, 4, 6, 19, 31, 73, 144, 331, 672, 1468, 3024, 6065, 9592, 19701, 39630, 79625, 157569, 316139, 632655, 1264043, 2532963, 5060484, 10128862, 20270752, 40575156, 81134041, 162268825, 324627203, 649177198, 1298516271, 2596827906

Offset

1,3

Links

Table of n, a(n) for n=1..32.

Example

n=4: between iv={1,2,...,16} {7,9,11,13,14,15} provides
peak values larger than 16, so a[4]=6.

Mathematica

c[x_]:=c[x]=(1-Mod[x, 2])*(x/2)+Mod[x, 2]*(3*x+1); c[1]=1; fpl[x_]:=FixedPointList[c, x]; {$RecursionLimit=1000; m=0}; Table[Print[{xm-1, m}]; m=0; Do[If[Greater[Max[fpl[n]], 2^xm], m=m+1], {n, 1, 2^xm}], {xm, 1, 30}]

Crossrefs

Cf. A087256, A095381, A095382, A095384.

Sequence in context: A034189 A024697 A024874 * A116383 A026521 A343677

Adjacent sequences: A095380 A095381 A095382 * A095384 A095385 A095386

Keyword

nonn

Author

Labos Elemer, Jun 14 2004

Extensions

a(22)-a(32) from Donovan Johnson, Feb 02 2011

Status

approved