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Equals 5*phi^2/6, phi being the golden ratio. - Stanislav Sykora, Nov 23 2013
Ivan Panchenko, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Icosahedron
Wikipedia, Icosahedron - Area and volume
Equals 5 * (3 + sqrt(5))/12.
RealDigits[N[5/12*(3+Sqrt), 200]][] (* Vladimir Joseph Stephan Orlovsky, Feb 21 2011 *)
Cf. A001622 (phi), A020829 (regular tetrahedron volume), A131594 (regular octahedron volume), A102769 (regular dodecahedron volume).
Sequence in context: A230369 A254027 A083529 * A125911 A009385 A008308
Adjacent sequences: A102205 A102206 A102207 * A102209 A102210 A102211
Bryan Jacobs (bryanjj(AT)gmail.com), Feb 17 2005