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A006269
A continued cotangent.
(Formerly M4028)
12
5, 140, 2744420, 20670535451567121260, 8831921094058107711185956797335984862612406515067837739780
OFFSET
0,1
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Jeffrey Shallit, Predictable regular continued cotangent expansions, J. Res. Nat. Bur. Standards Sect. B 80B (1976), no. 2, 285-290.
FORMULA
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)
MATHEMATICA
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 *)
CROSSREFS
Sequence in context: A193756 A136464 A203523 * A066264 A171776 A277401
KEYWORD
nonn
AUTHOR
STATUS
approved