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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
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
Mauro Fiorentini, Construibili (numeri)
Eric Weisstein's World of Mathematics, 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
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: A274400 A200495 A329937 * A016626 A126321 A335777
KEYWORD
nonn,cons,easy
AUTHOR
Stanislav Sykora, May 02 2016
STATUS
approved