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 A062058 Numbers with 8 odd integers in their Collatz (or 3x+1) trajectory. 3
 25, 49, 50, 51, 98, 99, 100, 101, 102, 196, 197, 198, 200, 202, 204, 205, 217, 392, 394, 396, 397, 400, 404, 405, 408, 410, 433, 434, 435, 441, 475, 784, 788, 789, 792, 794, 800, 808, 810, 816, 820, 821, 833, 857, 866, 867, 868, 869, 870, 875, 882, 883, 950, 951, 953 (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. Sequence is 2-automatic. A078719(a(n)) = 8; A006667(a(n)) = 7. 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, CollatzProblem Wikipedia, Collatz conjecture EXAMPLE The Collatz trajectory of 25 is (25, 76, 38, 19, 58, 29, 88, 44, 22, 11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1), which contains 8 odd integers. MATHEMATICA Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; countOdd[lst_] := Length[Select[lst, OddQ]]; Select[Range[1000], countOdd[Collatz[#]] == 8 &] (* T. D. Noe, Dec 03 2012 *) PROG (Haskell) import Data.List (elemIndices) a062058 n = a062058_list !! (n-1) a062058_list = map (+ 1) \$ elemIndices 8 a078719_list -- Reinhard Zumkeller, Oct 08 2011 CROSSREFS Cf. A062052-A062060. Sequence in context: A106632 A090093 A004936 * A198591 A069063 A064937 Adjacent sequences:  A062055 A062056 A062057 * A062059 A062060 A062061 KEYWORD nonn AUTHOR STATUS approved

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