

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
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OFFSET

0,2


COMMENTS

This sequence is important for the computation of Collatz numbers. It shows that using 31bit integers, only numbers less than 159487 can have their Collatz trajectory computed.


LINKS



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



KEYWORD

nonn,base


AUTHOR



STATUS

approved



