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 A062055 Numbers with 5 odd integers in their Collatz (or 3x+1) trajectory. 5
 11, 22, 23, 44, 45, 46, 88, 90, 92, 93, 176, 180, 181, 184, 186, 201, 352, 360, 362, 368, 369, 372, 373, 401, 402, 403, 704, 720, 724, 725, 736, 738, 739, 744, 746, 753, 802, 803, 804, 805, 806, 1408, 1440, 1448, 1450, 1472, 1476, 1477, 1478, 1488, 1492, 1493, 1506 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The Collatz (or 3x+1) function is f(x) = x/2 if x is even, 3x+1 if x is odd. The Collatz trajectory of n is obtained by applying f repeatedly to n until 1 is reached. A078719(a(n)) = 5; A006667(a(n)) = 4. REFERENCES J. Shallit and D. Wilson, The "3x+1" Problem and Finite Automata, Bulletin of the EATCS #46 (1992) pp. 182-185. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..1000 J. Shallit and D. Wilson, The "3x+1" Problem and Finite Automata, Bulletin of the EATCS #46 (1992) pp. 182-185. Eric Weisstein's World of Mathematics, Collatz Problem Wikipedia, Collatz conjecture EXAMPLE The Collatz trajectory of 11 is (11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1), which contains 5 odd integers. MATHEMATICA Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; countOdd[lst_] := Length[Select[lst, OddQ]]; Select[Range[2000], countOdd[Collatz[#]] == 5 &] (* T. D. Noe, Dec 03 2012 *) PROG (Haskell) import Data.List (elemIndices) a062055 n = a062055_list !! (n-1) a062055_list = map (+ 1) \$ elemIndices 5 a078719_list -- Reinhard Zumkeller, Oct 08 2011 CROSSREFS Cf. A062052-A062060. Sequence in context: A297273 A296746 A095779 * A066500 A234314 A258738 Adjacent sequences:  A062052 A062053 A062054 * A062056 A062057 A062058 KEYWORD nonn AUTHOR STATUS approved

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Last modified December 10 20:38 EST 2019. Contains 329909 sequences. (Running on oeis4.)