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A008880 3x + 1 sequence starting at 33. 4
33, 100, 50, 25, 76, 38, 19, 58, 29, 88, 44, 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, 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 33; 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] &, 33, 100] (* Vincenzo Librandi, Jul 29 2014 *)

PROG

(MAGMA) [n eq 1 select 33 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

(Scala) def collatz(n: Int): Int = n % 2 match {

  case 0 => n / 2

  case _ => 3 * n + 1

}

def collatzSeq(n: Int): LazyList[Int] = LazyList.iterate(n)(collatz)

collatzSeq(33).take(100).toList // Alonso del Arte, Apr 25 2020

CROSSREFS

Cf. similar sequences listed in A245671.

Cf. A008896 (3x - 1 sequence starting at 66).

Sequence in context: A032650 A284986 A133901 * A045613 A033574 A183446

Adjacent sequences:  A008877 A008878 A008879 * A008881 A008882 A008883

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified November 23 14:26 EST 2020. Contains 338590 sequences. (Running on oeis4.)