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 A386754 #10 Aug 02 2025 09:59:04 %S A386754 1,6,3,8,8,6,7,3,5,3,7,7,1,9,0,6,7,9,1,2,5,3,2,4,0,6,0,5,4,3,1,8,7,2, %T A386754 2,5,4,1,2,0,0,4,4,7,4,6,5,6,2,9,9,0,2,9,7,0,8,8,6,3,6,7,2,7,3,4,6,8, %U A386754 2,8,8,8,0,6,9,4,3,6,9,8,8,7,0,1,3,2,7,6,8,1 %N A386754 Decimal expansion of the surface area of a triangular hebesphenorotunda with unit edges. %C A386754 The triangular hebesphenorotunda is Johnson solid J_92. %H A386754 Paolo Xausa, <a href="/A386754/b386754.txt">Table of n, a(n) for n = 2..10000</a> %H A386754 Wikipedia, <a href="https://en.wikipedia.org/wiki/Triangular_hebesphenorotunda">Triangular hebesphenorotunda</a>. %F A386754 Equals (12 + 19*sqrt(3) + 3*sqrt(5*(5 + 2*sqrt(5))))/4 = (12 + 19*A002194 + 3*sqrt(5*(5 + A010476)))/4. %F A386754 Equals the largest root of 256*x^8 - 6144*x^7 - 19200*x^6 + 1119744*x^5 - 1614816*x^4 - 57096576*x^3 + 76850100*x^2 + 856278216*x + 56001861. %e A386754 16.3886735377190679125324060543187225412004474656... %t A386754 First[RealDigits[(12 + 19*A002194 + 3*Sqrt[5*(5 + A010476)])/4, 10, 100]] (* or *) %t A386754 First[RealDigits[PolyhedronData["J92", "SurfaceArea"], 10, 100]] %Y A386754 Cf. A176324 (volume). %Y A386754 Cf. A002194, A010476. %K A386754 nonn,cons,easy %O A386754 2,2 %A A386754 _Paolo Xausa_, Aug 01 2025