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A222292 Least number whose Collatz 3x+1 trajectory contains a number >= 2^n. 3

%I

%S 1,3,3,3,3,7,15,15,27,27,27,27,27,27,447,447,703,703,1819,1819,1819,

%T 4255,4255,9663,9663,20895,26623,60975,60975,60975,77671,113383,

%U 159487,159487,159487,665215,1042431,1212415,2684647,3041127,4637979,5656191,6416623

%N Least number whose Collatz 3x+1 trajectory contains a number >= 2^n.

%C Are the unique values a subset of A006884? - _Ralf Stephan_, May 27 2013

%C 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.

%H T. D. Noe, <a href="/A222292/b222292.txt">Table of n, a(n) for n = 0..63</a>

%H Eric Roosendaal, <a href="http://www.ericr.nl/wondrous/pathrecs.html">3x+1 path records</a>

%t 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 *)

%Y Cf. A222291 (base-10 version).

%Y Cf. A095384.

%K nonn,base

%O 0,2

%A _T. D. Noe_, Feb 19 2013

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Last modified April 7 12:36 EDT 2020. Contains 333305 sequences. (Running on oeis4.)