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A039500
Iterations of "k->k/2 if k is even, k->3k-1 if k is 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
OFFSET
1,2
COMMENTS
It appears that lim_{n->oo} 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
There are 327679 terms in this sequence which are less than 1000000. Based on this, I would suggest that the limit of a(n)/n is more likely to be 3 than 5/2. This is also a natural guess; there are three known periodic orbits for this recurrence. - David Speyer, Mar 25 2022
LINKS
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.
Sequence in context: A293635 A123586 A257121 * A160649 A341059 A190203
KEYWORD
nonn,easy
AUTHOR
Christian G. Bower, Feb 15 1999
STATUS
approved