OFFSET
1,1
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
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
KEYWORD
nonn
AUTHOR
T. D. Noe, Oct 31 2011
STATUS
approved