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 A384215 #7 May 24 2025 01:58:52 %S A384215 1,8,4,8,8,6,8,1,1,6,2,5,9,0,5,7,6,5,6,5,2,4,0,6,0,9,1,5,5,9,4,8,7,5, %T A384215 7,9,9,1,8,5,3,3,7,0,0,1,9,8,0,5,7,9,9,2,8,6,6,3,2,3,9,4,3,7,3,2,4,1, %U A384215 1,3,0,0,4,1,4,6,8,2,1,4,2,6,3,1,0,6,5,0,6,0 %N A384215 Decimal expansion of the surface area of a gyroelongated square cupola with unit edge. %C A384215 The gyroelongated square cupola is Johnson solid J_23. %H A384215 Paolo Xausa, <a href="/A384215/b384215.txt">Table of n, a(n) for n = 2..10000</a> %H A384215 Wikipedia, <a href="https://en.wikipedia.org/wiki/Gyroelongated_square_cupola">Gyroelongated square cupola</a>. %F A384215 Equals 7 + 2*sqrt(2) + 5*sqrt(3) = 7 + A010466 + 5*A002194. %F A384215 Equals the largest root of x^4 - 28*x^3 + 128*x^2 + 952*x - 1244. %e A384215 18.4886811625905765652406091559487579918533700198... %t A384215 First[RealDigits[7 + Sqrt[8] + Sqrt[75], 10, 100]] (* or *) %t A384215 First[RealDigits[PolyhedronData["J23", "SurfaceArea"], 10, 100]] %Y A384215 Cf. A384214 (volume). %Y A384215 Cf. A002194, A010466. %K A384215 nonn,cons,easy %O A384215 2,2 %A A384215 _Paolo Xausa_, May 23 2025