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A039500 Iterations of "n->n/2 if n even, n->3n-1 if n odd" (A001281) starting at these numbers reach 1. 13
1, 2, 3, 4, 6, 8, 11, 12, 15, 16, 22, 24, 29, 30, 32, 39, 43, 44, 48, 53, 57, 58, 59, 60, 64, 65, 69, 71, 77, 78, 79, 85, 86, 87, 88, 95, 96, 97, 101, 103, 105, 106, 113, 114, 115, 116, 118, 120, 127, 128, 129, 130, 135, 137, 138, 141, 142, 145, 151, 154, 155, 156 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

It appears that lim_{n->infinity} a(n)/n = 5/2. - Benoit Cloitre, Jan 29 2006

Equivalent to the Collatz ('3n+1') problem for negative integers. - Dmitry Kamenetsky, Jan 12 2017

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..20000

MATHEMATICA

colln[n_]:= NestWhile[If[EvenQ[#], #/2, 3#-1] &, n, FreeQ[{1, 5, 17}, #] &]; Select[Range[156], colln[#] == 1 &] (* Jayanta Basu, Jun 06 2013 *)

CROSSREFS

Positive integers not in A037084.

Cf. A039501, A039502, A039503, A039504, A039505.

Sequence in context: A293635 A123586 A257121 * A160649 A341059 A190203

Adjacent sequences:  A039497 A039498 A039499 * A039501 A039502 A039503

KEYWORD

nonn,easy

AUTHOR

Christian G. Bower, Feb 15 1999

STATUS

approved

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Last modified May 8 08:51 EDT 2021. Contains 343666 sequences. (Running on oeis4.)