A003124 One of the basic cycles in the x->3x-1 (x odd) or x/2 (x even) problem.

17, 50, 25, 74, 37, 110, 55, 164, 82, 41, 122, 61, 182, 91, 272, 136, 68, 34, 17, 50, 25, 74, 37, 110, 55, 164, 82, 41, 122, 61, 182, 91, 272, 136, 68, 34, 17, 50, 25, 74, 37, 110, 55, 164, 82, 41, 122, 61, 182, 91, 272, 136, 68, 34

Offset

0,1

References

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

H.-O. Peitgen et al., Chaos and Fractals, Springer, p. 33.

Links

Table of n, a(n) for n=0..53.

Example

17 is odd, so the next term is 3 * 17 - 1 = 50.
50 is even, so the next term is 50/2 = 25.

Mathematica

Abs[NestList[If[EvenQ[#], #/2, 3# + 1]&, -17, 100]] (* Alonso del Arte, May 19 2015 *)

Prog

(PARI) a=34; A003124=vector(100, i, a=if(bittest(a, 0), 3*a-1, a/2)) \\ M. F. Hasler, Aug 29 2015
(PARI) A003124(n, a=17)={for(i=1, n%17, a=if(bittest(a, 0), 3*a-1, a\2)); a} \\ M. F. Hasler, Aug 29 2015

Crossrefs

Sequence in context: A146461 A098329 A160076 * A005570 A195037 A214660

Adjacent sequences: A003121 A003122 A003123 * A003125 A003126 A003127

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved