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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A008877 3x+1 sequence starting at 57. 2
57, 172, 86, 43, 130, 65, 196, 98, 49, 148, 74, 37, 112, 56, 28, 14, 7, 22, 11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1, 4, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, E16.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

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

Index entries for linear recurrences with constant coefficients, signature (0, 0, 1).

MAPLE

f := proc(n) option remember; if n = 0 then 57; elif f(n-1) mod 2 = 0 then f(n-1)/2 else 3*f(n-1)+1; fi; end;

MATHEMATICA

NestList[If[EvenQ[#], #/2, 3# + 1]&, 57, 100] (* Vincenzo Librandi, Jul 29 2014 *)

PROG

(Haskell)

a008877 n = a008877_list !! n

a008877_list = 57 : iterate a006370 57

-- Reinhard Zumkeller, Aug 30 2012

(MAGMA) [n eq 1 select 57 else IsOdd(Self(n-1)) select 3*Self(n-1)+1 else Self(n-1) div 2: n in [1..80]]; // Vincenzo Librandi, Jul 29 2014

CROSSREFS

Cf. A006370.

Sequence in context: A250606 A044389 A044770 * A277805 A158660 A158668

Adjacent sequences:  A008874 A008875 A008876 * A008878 A008879 A008880

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

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 July 23 22:38 EDT 2019. Contains 325278 sequences. (Running on oeis4.)