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 A378823 #12 Dec 10 2024 05:46:47 %S A378823 5,4,7,9,6,5,4,9,4,3,8,6,5,9,6,9,3,3,9,7,6,3,5,0,2,3,1,5,2,5,9,0,1,9, %T A378823 0,9,0,8,7,0,8,6,4,4,3,9,8,5,2,3,7,0,6,8,8,8,2,1,3,8,0,5,9,7,0,3,6,8, %U A378823 0,1,7,8,0,1,1,5,2,1,6,8,3,8,7,4,3,0,0,5,7,8 %N A378823 Decimal expansion of the surface area of a pentagonal icositetrahedron with unit shorter edge length. %C A378823 The pentagonal icositetrahedron is the dual polyhedron of the snub cube. %H A378823 Paolo Xausa, <a href="/A378823/b378823.txt">Table of n, a(n) for n = 2..10000</a> %H A378823 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PentagonalIcositetrahedron.html">Pentagonal Icositetrahedron</a>. %H A378823 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentagonal_icositetrahedron">Pentagonal icositetrahedron</a>. %F A378823 Equals 24*(1 + s)^2*(2 + 3*s)/(1 + 2*s)*sqrt((1 - s)/(1 + s)), where s = (A058265 - 1)/2. %F A378823 Equals the positive real root of x^6 - 3060*x^4 + 185328*x^2 - 39517632. %e A378823 54.79654943865969339763502315259019090870864439852... %t A378823 First[RealDigits[Root[#^6 - 3060*#^4 + 185328*#^2 - 39517632 &, 2], 10, 100]] (* or *) %t A378823 First[RealDigits[PolyhedronData["PentagonalIcositetrahedron", "SurfaceArea"], 10, 100]] %Y A378823 Cf. A378824 (volume), A378825 (inradius), A378826 (midradius), A378827 (dihedral angle). %Y A378823 Cf. A377602 (surface area of a snub cube with unit edge length). %Y A378823 Cf. A058265. %K A378823 nonn,cons,easy %O A378823 2,1 %A A378823 _Paolo Xausa_, Dec 09 2024