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A062055
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Numbers with 5 odd integers in their Collatz (or 3x+1) trajectory.
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3
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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; internal format)
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OFFSET
| 1,1
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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)) = 5; A006667(a(n)) = 4.
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REFERENCES
| J. Shallit and D. Wilson, The "3x+1" Problem and Finite Automata, Bulletin of the EATCS #46 (1992) pp. 182-185.
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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
Index entries for sequences related to 3x+1 (or Collatz) problem
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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.
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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
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CROSSREFS
| Cf. A062052-A062060.
Sequence in context: A180054 A166713 A095779 * A066500 A160272 A164006
Adjacent sequences: A062052 A062053 A062054 * A062056 A062057 A062058
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KEYWORD
| nonn
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AUTHOR
| David W. Wilson (davidwwilson(AT)comcast.net)
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