This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A102208 #38 Feb 16 2025 08:32:55 %S A102208 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, %T A102208 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, %U A102208 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 %N A102208 Decimal expansion of the volume of an icosahedron with unit edge length. %D A102208 Jan Gullberg, Mathematics from the Birth of Numbers, W. W. Norton & Co., NY & London, 1997, ยง12.4 Theorems and Formulas (Solid Geometry), p. 451. %H A102208 Ivan Panchenko, <a href="/A102208/b102208.txt">Table of n, a(n) for n = 1..1000</a> %H A102208 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Icosahedron.html">Icosahedron</a>. %H A102208 Wikipedia, <a href="http://en.wikipedia.org/wiki/Icosahedron#Area_and_volume">Icosahedron - Area and volume</a>. %H A102208 <a href="/index/Al#algebraic_02">Index entries for algebraic numbers, degree 2</a>. %F A102208 Equals 5 * (3 + sqrt(5))/12. %F A102208 Equals 5*phi^2/6, phi being the golden ratio. - _Stanislav Sykora_, Nov 23 2013 %e A102208 2.181694990624912373503822... %t A102208 RealDigits[5/12*(3+Sqrt[5]),10, 200][[1]] (* _Vladimir Joseph Stephan Orlovsky_, Feb 21 2011 *) %o A102208 (PARI) 5*(3 + sqrt(5))/12 \\ _G. C. Greubel_, Jul 06 2017 %Y A102208 Cf. A001622 (phi), A020829 (regular tetrahedron volume), A131594 (regular octahedron volume), A102769 (regular dodecahedron volume). %Y A102208 Cf. A071402. %K A102208 cons,easy,nonn %O A102208 1,1 %A A102208 Bryan Jacobs (bryanjj(AT)gmail.com), Feb 17 2005