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A102208 Decimal expansion of volume of an icosahedron with each edge of unit length. 31
2, 1, 8, 1, 6, 9, 4, 9, 9, 0, 6, 2, 4, 9, 1, 2, 3, 7, 3, 5, 0, 3, 8, 2, 2, 3, 6, 1, 9, 7, 1, 3, 6, 5, 0, 9, 8, 1, 0, 0, 2, 5, 7, 6, 4, 9, 8, 3, 8, 1, 3, 5, 7, 1, 8, 4, 4, 6, 2, 0, 7, 1, 8, 5, 5, 8, 7, 7, 1, 7, 0, 5, 2, 3, 4, 9, 0, 8, 5, 3, 7, 4, 7, 5, 6, 0, 0, 6, 0, 0, 3, 4, 9, 1, 1, 5, 9, 2, 8, 1 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Ivan Panchenko, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Icosahedron

Wikipedia, Icosahedron - Area and volume

FORMULA

Equals 5 * (3 + sqrt(5))/12.

Equals 5*phi^2/6, phi being the golden ratio. - Stanislav Sykora, Nov 23 2013

EXAMPLE

2.181694990624912373503822...

MATHEMATICA

RealDigits[N[5/12*(3+Sqrt[5]), 200]][[1]] (* Vladimir Joseph Stephan Orlovsky, Feb 21 2011 *)

PROG

(PARI) 5*(3 + sqrt(5))/12 \\ G. C. Greubel, Jul 06 2017

CROSSREFS

Cf. A001622 (phi), A020829 (regular tetrahedron volume), A131594 (regular octahedron volume), A102769 (regular dodecahedron volume).

Sequence in context: A254027 A284346 A083529 * A125911 A009385 A008308

Adjacent sequences:  A102205 A102206 A102207 * A102209 A102210 A102211

KEYWORD

cons,nonn

AUTHOR

Bryan Jacobs (bryanjj(AT)gmail.com), Feb 17 2005

STATUS

approved

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Last modified July 20 16:53 EDT 2017. Contains 289628 sequences.