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A006269
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A continued cotangent.
(Formerly M4028)
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11
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OFFSET
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0,1
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Table of n, a(n) for n=0..4.
Jeffrey Shallit, Predictable regular continued cotangent expansions, J. Res. Nat. Bur. Standards Sect. B 80B (1976), no. 2, 285-290.
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FORMULA
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From Artur Jasinski, Oct 03 2008: (Start)
Recurrence: a(n+1)=a(n)^3+3*a(n) and a(0)=5.
a(n) = round((5/2 + sqrt(29)/2)^(3^(n - 1))). (End)
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MATHEMATICA
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a = {}; k = 5; Do[AppendTo[a, k]; k = k^3 + 3 k, {n, 1, 8}]; a (* Artur Jasinski, Oct 03 2008 *)
Table[Round[(5/2 + Sqrt[29]/2)^(3^(n - 1))], {n, 1, 8}] (* Artur Jasinski, Oct 03 2008 *)
NestList[#^3+3#&, 5, 5] (* Harvey P. Dale, Feb 14 2013 *)
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CROSSREFS
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Sequence in context: A193756 A136464 A203523 * A066264 A171776 A277401
Adjacent sequences: A006266 A006267 A006268 * A006270 A006271 A006272
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane.
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STATUS
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approved
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