login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A182078 Odd numbers n such that the reduced Collatz map n -> (3n+1)/2^k gives a trajectory of decreasing odd numbers. 0
5, 13, 17, 21, 45, 53, 69, 85, 113, 141, 181, 213, 241, 277, 301, 321, 341, 369, 401, 453, 565, 725, 753, 853, 909, 965, 1069, 1109, 1137, 1205, 1285, 1365, 1425, 1477, 1605, 1713, 1813, 1933, 1969, 2261, 2417, 2573, 2577, 2625, 2901, 2957, 3013, 3213, 3413 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..49.

EXAMPLE

45 is in the sequence because 45 generates the trajectory of odd numbers : 45 -> 17 -> -> 13 -> 5 -> 1.

MAPLE

for n from 3 by 2 to 5000 do:i:=0:x:=n:n0:=n: u0:=0:for it from 1 to 1000 while(n0<>1 and u0=0) do: for a from 1 to 100 while(x mod 2 = 0 ) do: i:=i+1:x:=x/2: od:if x > n0 then u0:=1:else i:=i+1:n0:=x :x:=3*n0+1: fi:od: if u0=0 then printf(`%d, `, n):else fi:od:

CROSSREFS

Cf. A006666, A075677 (reduced Collatz map).

Sequence in context: A014539 A249034 A208883 * A074278 A087895 A092101

Adjacent sequences:  A182075 A182076 A182077 * A182079 A182080 A182081

KEYWORD

nonn

AUTHOR

Michel Lagneau, Apr 10 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 21 00:17 EDT 2019. Contains 327252 sequences. (Running on oeis4.)