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 A384871 #10 Jun 12 2025 08:36:58 %S A384871 9,2,4,1,8,0,8,2,8,6,4,5,7,8,9,5,2,0,0,8,5,2,4,4,5,1,4,3,1,9,0,1,5,8, %T A384871 8,2,3,8,3,4,6,2,1,5,8,2,5,2,4,0,1,1,9,2,5,5,6,4,3,6,9,2,6,1,2,7,1,9, %U A384871 1,8,5,9,5,0,7,8,7,6,0,2,0,7,1,1,3,3,6,3,3,5 %N A384871 Decimal expansion of the volume of a pentagonal orthocupolarotunda with unit edge. %C A384871 The pentagonal orthocupolarotunda is Johnson solid J_32. %C A384871 Also the volume of a pentagonal gyrocupolarotunda (Johnson solid J_33) with unit edge. %H A384871 Paolo Xausa, <a href="/A384871/b384871.txt">Table of n, a(n) for n = 1..10000</a> %H A384871 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentagonal_gyrocupolarotunda">Pentagonal gyrocupolarotunda</a>. %H A384871 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentagonal_orthocupolarotunda">Pentagonal orthocupolarotunda</a>. %F A384871 Equals (5/12)*(11 + 5*sqrt(5)) = (5/12)*(11 + 5*A002163). %F A384871 Equals the largest root of 36*x^2 - 330*x - 25. %e A384871 9.2418082864578952008524451431901588238346215825240... %t A384871 First[RealDigits[5*(11 + 5*Sqrt[5])/12, 10, 100]] (* or *) %t A384871 First[RealDigits[PolyhedronData["J32", "Volume"], 10, 100]] %Y A384871 Cf. A384872 (surface area). %Y A384871 Cf. A002163, A384144, A384283, A384285, A384624. %K A384871 nonn,cons,easy %O A384871 1,1 %A A384871 _Paolo Xausa_, Jun 11 2025