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%I #19 Aug 11 2019 00:03:24
%S 1,2,4,8,16,21,32,42,64,75,84,85,113,128,150,151,168,170,201,226,227,
%T 256,267,300,301,302,336,340,341,401,402,403,423,452,453,454,475,512,
%U 534,535,537,600,602,604,605,633,635,672,680,682,713,715,802,803,804,805,806,846,847,891,904,906,908,909,950,951,953,955
%N Positive integers with Collatz trajectories that do not include the number 5.
%C A consequence of the Collatz conjecture is that, after a(5), this would be equivalent to the list of positive integers with Collatz trajectories that include the number 32.
%H Anonymous, <a href="http://archive.fo/IyVtW">Archive of /sci/ - Conjecture</a>.
%H <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>
%e 21 is a term because its Collatz trajectory, given in A033481, does not include 5.
%t collatzTrajectory[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; Select[Range[1000], Not[MemberQ[collatzTrajectory[#], 5]] &] (* _Alonso del Arte_, May 25 2019 *)
%Y Cf. A006370, A033481, A070165.
%Y A000079 is a subsequence.
%K nonn,easy
%O 1,2
%A _Nathan Bumber_, May 14 2019
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