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A308149 Positive integers with Collatz trajectories that do not include the number 5. 0
1, 2, 4, 8, 16, 21, 32, 42, 64, 75, 84, 85, 113, 128, 150, 151, 168, 170, 201, 226, 227, 256, 267, 300, 301, 302, 336, 340, 341, 401, 402, 403, 423, 452, 453, 454, 475, 512, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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.

LINKS

Table of n, a(n) for n=1..68.

Anonymous, Archive of /sci/ - Conjecture.

Index entries for sequences related to 3x+1 (or Collatz) problem

EXAMPLE

21 is a term because its Collatz trajectory, given in A033481, does not include 5.

MATHEMATICA

collatzTrajectory[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; Select[Range[1000], Not[MemberQ[collatzTrajectory[#], 5]] &] (* Alonso del Arte, May 25 2019 *)

CROSSREFS

Cf. A006370, A033481, A070165.

A000079 is a subsequence.

Sequence in context: A045776 A102252 A174838 * A196871 A334423 A001856

Adjacent sequences:  A308146 A308147 A308148 * A308150 A308151 A308152

KEYWORD

nonn,easy

AUTHOR

Nathan Bumber, May 14 2019

STATUS

approved

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Last modified September 24 12:31 EDT 2021. Contains 347642 sequences. (Running on oeis4.)