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 A384911 #11 Jun 21 2025 11:43:28 %S A384911 3,3,5,3,8,5,3,2,3,3,2,5,0,6,0,5,8,3,1,0,0,4,1,0,0,7,6,2,2,3,6,7,2,8, %T A384911 8,5,7,1,8,8,7,1,3,8,8,9,1,8,6,0,3,1,5,6,5,9,6,5,8,9,3,9,1,2,2,1,1,1, %U A384911 8,3,1,7,5,8,8,7,0,7,6,3,7,5,8,3,8,1,3,8,6,8 %N A384911 Decimal expansion of the surface area of an elongated pentagonal orthocupolarotunda with unit edge. %C A384911 The elongated pentagonal orthocupolarotunda is Johnson solid J_40. %C A384911 Also the surface area of an elongated pentagonal gyrocupolarotunda (Johnson solid J_41) with unit edge. %H A384911 Paolo Xausa, <a href="/A384911/b384911.txt">Table of n, a(n) for n = 2..10000</a> %H A384911 Wikipedia, <a href="https://en.wikipedia.org/wiki/Elongated_pentagonal_gyrocupolarotunda">Elongated pentagonal gyrocupolarotunda</a>. %H A384911 Wikipedia, <a href="https://en.wikipedia.org/wiki/Elongated_pentagonal_orthocupolarotunda">Elongated pentagonal orthocupolarotunda</a>. %F A384911 Equals (60 + sqrt(10*(190 + 49*sqrt(5) + 21*sqrt(75 + 30*sqrt(5)))))/4 = (60 + sqrt(10*(190 + 49*A002163 + 21*sqrt(75 + 30*A002163))))/4. %F A384911 Equals the largest root of 256*x^8 - 30720*x^7 + 1491200*x^6 - 37440000*x^5 + 509444000*x^4 - 3437040000*x^3 + 5993612500*x^2 + 44939625000*x - 172099671875. %e A384911 33.538532332506058310041007622367288571887138891860... %t A384911 First[RealDigits[(60 + Sqrt[10*(190 + 49*Sqrt[5] + 21*Sqrt[75 + 30*Sqrt[5]])])/4, 10, 100]] (* or *) %t A384911 First[RealDigits[PolyhedronData["J40", "SurfaceArea"], 10, 100]] %Y A384911 Cf. A384910 (volume). %Y A384911 Cf. A002163, A384284, A384286, A384625. %Y A384911 Apart from the leading digit the same as A384872. %K A384911 nonn,cons,easy %O A384911 2,1 %A A384911 _Paolo Xausa_, Jun 13 2025