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A222292 Least number whose Collatz 3x+1 trajectory contains a number >= 2^n. 3
1, 3, 3, 3, 3, 7, 15, 15, 27, 27, 27, 27, 27, 27, 447, 447, 703, 703, 1819, 1819, 1819, 4255, 4255, 9663, 9663, 20895, 26623, 60975, 60975, 60975, 77671, 113383, 159487, 159487, 159487, 665215, 1042431, 1212415, 2684647, 3041127, 4637979, 5656191, 6416623 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
Are the unique values a subset of A006884? - Ralf Stephan, May 27 2013
This sequence is important for the computation of Collatz numbers. It shows that using 31-bit integers, only numbers less than 159487 can have their Collatz trajectory computed.
LINKS
Eric Roosendaal, 3x+1 path records
MATHEMATICA
mcoll[n_]:=Max@@NestWhileList[If[EvenQ[#], #/2, 3#+1] &, n, #>1 &]; i=1; Join[{1, 3}, Table[i=i; While[mcoll[i]<2^n, i=i+2]; i, {n, 2, 30}]] (* Jayanta Basu, May 27 2013 *)
CROSSREFS
Cf. A222291 (base-10 version).
Cf. A095384.
Sequence in context: A098528 A242715 A078229 * A245441 A333793 A007428
KEYWORD
nonn,base
AUTHOR
T. D. Noe, Feb 19 2013
STATUS
approved

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Last modified May 25 22:55 EDT 2024. Contains 372806 sequences. (Running on oeis4.)