A256854 Decimal expansion of area of a regular 11-gon with unit edge length.

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

Offset

1,1

Links

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

Wikipedia, Hendecagon

Wikipedia, Regular polygon

Index entries for algebraic numbers, degree 10

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 A309602

Adjacent sequences: A256851 A256852 A256853 * A256855 A256856 A256857

Keyword

nonn,cons

Author

Stanislav Sykora, Apr 12 2015

Status

approved