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A008879 3x+1 sequence starting at 87. 3
87, 262, 131, 394, 197, 592, 296, 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, 4 (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 87; 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]&, 87, 100] (* Vincenzo Librandi, Jul 29 2014 *)

PROG

(MAGMA) [n eq 1 select 87 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. similar sequences listed in A245671.

Sequence in context: A304509 A020314 A008899 * A186063 A186055 A243580

Adjacent sequences:  A008876 A008877 A008878 * A008880 A008881 A008882

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified July 23 14:27 EDT 2019. Contains 325254 sequences. (Running on oeis4.)