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A272535 Decimal expansion of the edge length of a regular 16-gon with unit circumradius. 4
3, 9, 0, 1, 8, 0, 6, 4, 4, 0, 3, 2, 2, 5, 6, 5, 3, 5, 6, 9, 6, 5, 6, 9, 7, 3, 6, 9, 5, 4, 0, 4, 4, 4, 8, 1, 8, 5, 5, 3, 8, 3, 2, 3, 5, 5, 0, 3, 9, 0, 9, 6, 1, 5, 5, 0, 9, 0, 0, 4, 1, 7, 8, 9, 8, 9, 5, 2, 6, 6, 3, 7, 5, 7, 1, 8, 4, 9, 1, 6, 0, 4, 5, 0, 6, 5, 0, 6, 1, 8, 4, 6, 8, 1, 8, 0, 7, 6, 3, 4, 6, 1, 9, 8, 4 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Like all m-gons with m equal to a power of 2 (see A003401 and A000079), this is a constructible number.

LINKS

Stanislav Sykora, Table of n, a(n) for n = 0..2000

Mauro Fiorentini, Construibili (numeri)

Eric Weisstein's World of Mathematics, Constructible Number

Wikipedia, Constructible number

Wikipedia, Regular polygon

FORMULA

Equals 2*sin(Pi/m) for m=16. Equals also sqrt(2-sqrt(2+sqrt(2))).

EXAMPLE

0.390180644032256535696569736954044481855383235503909615509004...

MATHEMATICA

RealDigits[N[2Sin[Pi/16], 100]][[1]] (* Robert Price, May 02 2016*)

PROG

(PARI) 2*sin(Pi/16)

CROSSREFS

Cf. A000079, A003401.

Edge lengths of other constructible m-gons: A002194 (m=3), A002193 (4), A182007 (5), A101464 (8), A094214 (10), A101263 (12), A272534 (15), A228787 (17), A272536 (20).

Sequence in context: A247042 A274400 A200495 * A016626 A126321 A248726

Adjacent sequences:  A272532 A272533 A272534 * A272536 A272537 A272538

KEYWORD

nonn,cons,easy

AUTHOR

Stanislav Sykora, May 02 2016

STATUS

approved

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Last modified August 22 12:56 EDT 2017. Contains 290948 sequences.