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A198592
Odd numbers producing 9 odd numbers in the Collatz iteration.
1
33, 65, 67, 131, 133, 261, 269, 273, 289, 525, 529, 533, 547, 555, 571, 577, 579, 583, 633, 635, 1045, 1059, 1077, 1093, 1099, 1111, 1143, 1155, 1157, 1167, 1177, 1267, 1271, 1273, 2101, 2117, 2123, 2133, 2161, 2189, 2199, 2221, 2285, 2309, 2317, 2321, 2333
OFFSET
1,1
MATHEMATICA
Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; t = {}; Do[If[Length[Select[Collatz[n], OddQ]] == 9, AppendTo[t, n]], {n, 1, 10000, 2}]; t
col9Q[n_]:=Count[NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n, #!=1&], _?(OddQ[#]&)]==9; Select[ Range[1, 2501, 2], col9Q] (* Harvey P. Dale, Dec 10 2023 *)
CROSSREFS
Cf. A198584.
Sequence in context: A331071 A062059 A285317 * A325377 A061560 A118618
KEYWORD
nonn
AUTHOR
T. D. Noe, Oct 31 2011
STATUS
approved