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 A386753 #9 Aug 02 2025 08:42:15 %S A386753 1,2,3,4,6,0,1,1,2,1,7,4,9,3,6,2,2,2,7,8,0,9,0,9,4,0,5,9,2,5,6,6,1,8, %T A386753 3,1,3,1,5,1,5,1,0,7,1,8,7,6,6,1,5,5,4,5,7,2,9,3,9,9,9,2,7,8,6,9,9,9, %U A386753 3,4,2,0,0,2,6,5,3,4,6,4,9,9,9,4,9,2,0,5,7,3 %N A386753 Decimal expansion of the surface area of a bilunabirotunda with unit edges. %C A386753 The bilunabirotunda is Johnson solid J_91. %H A386753 Paolo Xausa, <a href="/A386753/b386753.txt">Table of n, a(n) for n = 2..10000</a> %H A386753 Wikipedia, <a href="https://en.wikipedia.org/wiki/Bilunabirotunda">Bilunabirotunda</a>. %F A386753 Equals 2 + 2*sqrt(3) + sqrt(5*(5 + 2*sqrt(5))) = 2 + A010469 + sqrt(5*(5 + A010476)). %F A386753 Equals the largest root of x^8 - 16*x^7 - 36*x^6 + 1328*x^5 - 2946*x^4 - 16624*x^3 + 34796*x^2 + 61392*x - 10679. %e A386753 12.346011217493622278090940592566183131515107... %t A386753 First[RealDigits[2 + Sqrt[12] + Sqrt[5*(5 + Sqrt[20])], 10, 100]] (* or *) %t A386753 First[RealDigits[PolyhedronData["J91", "SurfaceArea"], 10, 100]] %Y A386753 Cf. A189963 (volume - 1). %Y A386753 Cf. A010469, A010476. %K A386753 nonn,cons,easy %O A386753 2,2 %A A386753 _Paolo Xausa_, Aug 01 2025