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A006268 A continued cotangent.
(Formerly M3141)
12
3, 36, 46764, 102266868132036, 1069559300034650646049671039050649693658764, 1223529951178258250171873770392800315927007484424019792314038900599526596342245441950466608853108106356422588162773879214824036 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

a(6)=1223529951178258250171873770392800315927007484424019792314038900\

599526596342245441950466608853108106356422588162773879214824036 Artur Jasinski, Oct 03 2008

REFERENCES

Shallit, Jeffrey; Predictable regular continued cotangent expansions. J. Res. Nat. Bur. Standards Sect. B 80B (1976), no. 2, 285-290.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=0..5.

FORMULA

Recurrence: a(n+1)=a(n)^3+3a(n) and a(0)=3 a(n)=Round[(3/2 + Sqrt[13]/2)^(3^(n - 1))] [From Artur Jasinski, Oct 03 2008]

MATHEMATICA

Contribution from Artur Jasinski, Oct 03 2008: (Start)

a = {}; k = 3; Do[AppendTo[a, k]; k = k^3 + 3 k, {n, 1, 6}]; a

or

Table[Round[N[(3/2 + Sqrt[13]/2)^(3^(n - 1)), 1000]], {n, 1, 8}] (*Artur Jasinski*) (End)

CROSSREFS

Sequence in context: A262825 A088322 A080807 * A264842 A210508 A073236

Adjacent sequences:  A006265 A006266 A006267 * A006269 A006270 A006271

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified April 19 19:07 EDT 2019. Contains 322290 sequences. (Running on oeis4.)