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A308149
Positive integers with Collatz trajectories that do not include the number 5.
2
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
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.
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
A000079 is a subsequence.
Sequence in context: A045776 A102252 A174838 * A196871 A334423 A375006
KEYWORD
nonn,easy
AUTHOR
Nathan Bumber, May 14 2019
STATUS
approved