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A272535
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Decimal expansion of the edge length of a regular 16-gon with unit circumradius.
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4
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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
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OFFSET
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0,1
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COMMENTS
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Like all m-gons with m equal to a power of 2 (see A003401 and A000079), this is a constructible number.
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LINKS
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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
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FORMULA
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Equals 2*sin(Pi/m) for m=16. Equals also sqrt(2-sqrt(2+sqrt(2))).
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EXAMPLE
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0.390180644032256535696569736954044481855383235503909615509004...
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MATHEMATICA
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RealDigits[N[2Sin[Pi/16], 100]][[1]] (* Robert Price, May 02 2016*)
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PROG
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(PARI) 2*sin(Pi/16)
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CROSSREFS
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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
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KEYWORD
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nonn,cons,easy
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AUTHOR
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Stanislav Sykora, May 02 2016
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STATUS
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approved
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