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A256853 Decimal expansion of area of a regular 9-gon with unit edge length. 8
6, 1, 8, 1, 8, 2, 4, 1, 9, 3, 7, 7, 2, 9, 0, 0, 1, 2, 7, 2, 1, 3, 7, 4, 4, 0, 5, 9, 6, 1, 9, 7, 6, 3, 6, 1, 4, 9, 4, 1, 7, 1, 3, 3, 4, 8, 1, 3, 4, 3, 5, 8, 0, 9, 8, 3, 8, 6, 8, 6, 4, 2, 5, 5, 6, 6, 9, 7, 7, 1, 0, 7, 1, 2, 3, 3, 5, 8, 4, 6, 6, 4, 7, 6, 6, 3, 5, 9, 5, 5, 3, 3, 8, 9, 0, 7, 9, 1, 8, 4, 0, 9, 9, 0, 2 (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, Nonagon

Wikipedia, Regular polygon

FORMULA

Equals (p/4)*cot(Pi/p), with p = 9.

EXAMPLE

6.181824193772900127213744059619763614941713348134358098386864...

PROG

(PARI) p=9; a=(p/4)*cotan(Pi/p)        \\ Use realprecision in excess

CROSSREFS

Cf. A000796, A019968, A120011 (p=3), A102771 (p=5), A104956 (p=6), A178817 (p=7), A090488 (p=8), A178816 (p=10), A256854 (p=11), A178809 (p=12).

Sequence in context: A186099 A021622 A073228 * A258404 A244692 A248589

Adjacent sequences:  A256850 A256851 A256852 * A256854 A256855 A256856

KEYWORD

nonn,cons

AUTHOR

Stanislav Sykora, Apr 12 2015

STATUS

approved

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Last modified May 26 03:36 EDT 2017. Contains 287073 sequences.