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A256854 Decimal expansion of area of a regular 11-gon with unit edge length. 8
9, 3, 6, 5, 6, 3, 9, 9, 0, 6, 9, 4, 5, 4, 3, 7, 5, 2, 4, 8, 8, 2, 3, 5, 8, 4, 5, 3, 2, 8, 4, 3, 3, 4, 2, 8, 7, 8, 8, 2, 5, 7, 4, 9, 6, 1, 8, 3, 5, 0, 2, 7, 3, 8, 7, 6, 8, 9, 3, 1, 8, 6, 6, 7, 9, 4, 7, 8, 7, 0, 9, 3, 9, 8, 2, 3, 1, 0, 0, 7, 6, 4, 6, 1, 3, 0, 1, 3, 6, 4, 4, 1, 0, 4, 8, 1, 1, 2, 3, 0, 8, 3, 1, 1, 0 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Stanislav Sykora, Table of n, a(n) for n = 1..2000

Wikipedia, Hendecagon

Wikipedia, Regular polygon

FORMULA

Equals (p/4)*cot(Pi/p), with p = 11.

EXAMPLE

9.36563990694543752488235845328433428788257496183502738768931...

MATHEMATICA

RealDigits[11/4 Cot[Pi/11], 10, 120][[1]] (* Harvey P. Dale, Apr 03 2016 *)

PROG

(PARI) p=11; a=(p/4)*cotan(Pi/p)        \\ Use realprecision in excess

CROSSREFS

Cf. A000796, A120011 (p=3), A102771 (p=5), A104956 (p=6), A178817 (p=7), A090488 (p=8), A256853 (p=9), A178816 (p=10), A178809 (p=12).

Sequence in context: A182547 A019737 A088543 * A182552 A021985 A197832

Adjacent sequences:  A256851 A256852 A256853 * A256855 A256856 A256857

KEYWORD

nonn,cons

AUTHOR

Stanislav Sykora, Apr 12 2015

STATUS

approved

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Last modified June 27 17:44 EDT 2017. Contains 288790 sequences.