cp's OEIS Frontend

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

%I A222292 #40 Oct 31 2024 01:16:15
%S A222292 1,2,3,3,3,7,15,15,27,27,27,27,27,27,447,447,703,703,1819,1819,1819,
%T A222292 4255,4255,9663,9663,20895,26623,60975,60975,60975,77671,113383,
%U A222292 159487,159487,159487,665215,1042431,1212415,2684647,3041127,4637979,5656191,6416623
%N A222292 Least number whose Collatz 3x+1 trajectory contains a number >= 2^n.
%C A222292 Are the unique values a subset of A006884? - _Ralf Stephan_, May 27 2013
%C A222292 This sequence is important for the computation of Collatz numbers. It shows that using 32-bit integers, only numbers less than 159487 can have their Collatz trajectory computed.
%H A222292 T. D. Noe, <a href="/A222292/b222292.txt">Table of n, a(n) for n = 0..63</a>
%H A222292 Eric Roosendaal, <a href="http://www.ericr.nl/wondrous/pathrecs.html">3x+1 path records</a>
%H A222292 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%p A222292 b:= proc(n) option remember; `if`(n=1, 1,
%p A222292       max(n, b(`if`(n::even, n/2, 3*n+1))))
%p A222292     end:
%p A222292 a:= proc(n) option remember; local i, t; t:=2^n;
%p A222292       for i while b(i)<t do od: i
%p A222292     end:
%p A222292 seq(a(n), n=0..38);  # _Alois P. Heinz_, Sep 25 2024
%Y A222292 Cf. A025586, A222291 (base-10 version).
%Y A222292 Cf. A095384.
%K A222292 nonn,base
%O A222292 0,2
%A A222292 _T. D. Noe_, Feb 19 2013
%E A222292 a(1) corrected by _Kevin Ge_, Sep 25 2024