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A259193
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5x + 1 sequence beginning at 11.
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1
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11, 56, 28, 14, 7, 36, 18, 9, 46, 23, 116, 58, 29, 146, 73, 366, 183, 916, 458, 229, 1146, 573, 2866, 1433, 7166, 3583, 17916, 8958, 4479, 22396, 11198, 5599, 27996, 13998, 6999, 34996, 17498, 8749, 43746, 21873, 109366, 54683, 273416, 136708, 68354, 34177, 170886, 85443
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OFFSET
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0,1
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LINKS
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Alonso del Arte, Table of n, a(n) for n = 0..999
Alex V. Kontorovich & Jeffrey C. Lagarias, Stochastic Models for the 3x+1 and 5x+1 Problems arXiv:0910.1944 [math.NT], 2009.
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FORMULA
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a(0) = 11; a(n) = 5a(n - 1) + 1 if a(n - 1) is odd, a(n) = a(n - 1)/2 otherwise.
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EXAMPLE
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11 is odd, so it's followed by 5 * 11 + 1 = 56.
56 is even, so it's followed by 56/2 = 28.
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MATHEMATICA
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NestList[If[EvenQ[#], #/2, 5# + 1] &, 5, 100]
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PROG
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(MAGMA) [n eq 1 select 11 else IsOdd(Self(n-1)) select 5*Self(n-1)+1 else Self(n-1) div 2: n in [1..80]]; // Vincenzo Librandi, Jul 04 2015
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CROSSREFS
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Cf. A259207, A057688.
Sequence in context: A032166 A218000 A206528 * A099532 A041226 A042503
Adjacent sequences: A259190 A259191 A259192 * A259194 A259195 A259196
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KEYWORD
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nonn,easy
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AUTHOR
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Alonso del Arte, Jun 21 2015
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STATUS
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approved
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