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Search: id:A125710
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| A125710 |
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In the "3x+1" problem, let 0 denote a halving step and 1 denote an x->3x+1 step. Then a(n) is obtained by writing the sequence of steps needed to reach 1 from 2n+1 and reading it as a decimal number. |
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6
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| 4, 80, 16, 43280, 305424, 10512, 272, 87056, 2320, 665872, 64, 21520, 4860176, 1676649379371438023024192690344976, 141584, 54056611079304389108412587463696, 38414608, 5136, 1091856, 11358841104
(list; graph; listen)
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OFFSET
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0,1
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EXAMPLE
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7 -> 22 -> 11 -> 34 -> 17 -> 52 -> 26 -> 13 -> 40 -> 20 -> 10 -> 5 -> 16 -> 8 -> 4 -> 2 -> 1, so a(3) is the
decimal equivalent of 1010100100010000, which is 43280.
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MATHEMATICA
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f[x_] := If[EvenQ[x], x/2, 3x + 1]; g[n_] := FromDigits[Mod[Most[NestWhileList[f, 2n + 1, # > 1 &, {2, 1}]], 2], 2]; Table[g[n], {n, 0, 30}] (*Chandler*)
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CROSSREFS
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Cf. A125711, A125626.
Sequence in context: A006425 A065930 A018807 this_sequence A093854 A054322 A114488
Adjacent sequences: A125707 A125708 A125709 this_sequence A125711 A125712 A125713
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Feb 01 2007
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Feb 02 2007
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