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 A198590 Odd numbers producing 7 odd numbers in the Collatz iteration. 1
 9, 19, 37, 77, 81, 149, 163, 309, 321, 325, 331, 597, 625, 643, 653, 663, 713, 715, 1237, 1251, 1285, 1301, 1313, 1325, 1339, 1425, 1427, 1431, 1433, 2389, 2501, 2573, 2577, 2613, 2625, 2627, 2653, 2679, 2695, 2851, 2853, 2861, 2865, 2867, 4949, 5005, 5141 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1046 MATHEMATICA Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; t = {}; Do[If[Length[Select[Collatz[n], OddQ]] == 7, AppendTo[t, n]], {n, 1, 10000, 2}]; t CROSSREFS Cf. A198584. Sequence in context: A034056 A195042 A157034 * A297396 A145958 A290245 Adjacent sequences: A198587 A198588 A198589 * A198591 A198592 A198593 KEYWORD nonn AUTHOR T. D. Noe, Oct 31 2011 STATUS approved

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Last modified February 1 12:28 EST 2023. Contains 359993 sequences. (Running on oeis4.)