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 A385261 #7 Jun 29 2025 09:04:39 %S A385261 2,6,4,3,1,3,3,5,8,5,7,9,4,4,5,1,3,5,4,6,9,7,3,8,7,1,5,1,6,0,7,1,2,6, %T A385261 1,9,5,0,8,8,5,7,8,7,7,4,3,5,9,8,2,5,1,3,6,8,8,3,2,7,4,1,7,5,9,9,3,7, %U A385261 2,3,5,6,1,1,2,3,3,9,3,2,7,4,0,7,7,3,4,7,8,8 %N A385261 Decimal expansion of the surface area of a gyroelongated pentagonal bicupola with unit edge. %C A385261 The gyroelongated pentagonal bicupola is Johnson solid J_46. %H A385261 Paolo Xausa, <a href="/A385261/b385261.txt">Table of n, a(n) for n = 2..10000</a> %H A385261 Wikipedia, <a href="https://en.wikipedia.org/wiki/Gyroelongated_pentagonal_bicupola">Gyroelongated pentagonal bicupola</a>. %F A385261 Equals (20 + 15*sqrt(3) + sqrt(25 + 10*sqrt(5)))/2 = (20 + 15*A002194 + sqrt(25 + 10*A002163))/2. %F A385261 Equals the largest root of x^8 - 80*x^7 + 2100*x^6 - 14000*x^5 - 174750*x^4 + 1390000*x^3 + 9603125*x^2 + 9937500*x - 6546875. %e A385261 26.431335857944513546973871516071261950885787743598... %t A385261 First[RealDigits[(20 + 15*Sqrt[3] + Sqrt[25 + 10*Sqrt[5]])/2, 10, 100]] (* or *) %t A385261 First[RealDigits[PolyhedronData["J46", "SurfaceArea"], 10, 100]] %Y A385261 Cf. A385260 (volume). %Y A385261 Cf. A002163, A002194, A384284, A385257, A385259. %K A385261 nonn,cons,easy %O A385261 2,1 %A A385261 _Paolo Xausa_, Jun 27 2025