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 A384910 #8 Jun 17 2025 11:54:51 %S A384910 1,6,9,3,6,0,1,7,1,2,9,3,9,6,0,2,8,7,0,7,2,7,8,1,7,1,5,8,3,2,8,2,4,3, %T A384910 3,3,8,3,8,5,1,3,7,6,9,4,1,3,6,8,4,9,2,9,9,3,1,6,2,2,5,9,8,8,7,2,0,9, %U A384910 0,7,6,8,1,6,3,1,6,4,8,7,5,0,3,2,4,9,8,4,7,6 %N A384910 Decimal expansion of the volume of an elongated pentagonal orthocupolarotunda with unit edge. %C A384910 The elongated pentagonal orthocupolarotunda is Johnson solid J_40. %C A384910 Also the volume of an elongated pentagonal gyrocupolarotunda (Johnson solid J_41) with unit edge. %H A384910 Paolo Xausa, <a href="/A384910/b384910.txt">Table of n, a(n) for n = 2..10000</a> %H A384910 Wikipedia, <a href="https://en.wikipedia.org/wiki/Elongated_pentagonal_gyrocupolarotunda">Elongated pentagonal gyrocupolarotunda</a>. %H A384910 Wikipedia, <a href="https://en.wikipedia.org/wiki/Elongated_pentagonal_orthocupolarotunda">Elongated pentagonal orthocupolarotunda</a>. %F A384910 Equals (5/12)*(11 + 5*sqrt(5) + 6*sqrt(5 + 2*sqrt(5))) = (5/12)*(11 + 5*A002163 + 6*sqrt(5 + A010476)). %F A384910 Equals the largest root of 1296*x^4 - 23760*x^3 + 26100*x^2 + 84000*x - 111875. %e A384910 16.936017129396028707278171583282433383851376941... %t A384910 First[RealDigits[5/12*(11 + 5*Sqrt[5] + 6*Sqrt[5 + Sqrt[20]]), 10, 100]] (* or *) %t A384910 First[RealDigits[PolyhedronData["J40", "Volume"], 10, 100]] %Y A384910 Cf. A384911 (surface area). %Y A384910 Cf. A002163, A010476, A384283, A384285, A384624, A384871, A384909. %K A384910 nonn,cons,easy %O A384910 2,2 %A A384910 _Paolo Xausa_, Jun 13 2025