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 A384139 #13 Aug 04 2025 08:55:59 %S A384139 6,6,8,7,1,4,9,6,2,2,8,7,7,3,5,1,6,4,8,4,8,8,0,9,7,0,6,0,7,8,0,8,4,4, %T A384139 3,8,1,6,3,9,7,9,9,5,9,3,4,8,7,5,3,1,6,9,2,1,0,0,6,5,0,3,4,5,2,8,1,0, %U A384139 5,3,3,3,9,7,0,8,8,4,5,1,5,7,4,5,3,5,1,1,3,5 %N A384139 Decimal expansion of the volume of an elongated triangular bipyramid with unit edges. %C A384139 The elongated triangular bipyramid is Johnson solid J_14. %C A384139 Also the volume of an augmented triangular prism (Johnson solid J_49) with unit edges. - _Paolo Xausa_, Aug 04 2025 %H A384139 Paolo Xausa, <a href="/A384139/b384139.txt">Table of n, a(n) for n = 0..10000</a> %H A384139 Wikipedia, <a href="https://en.wikipedia.org/wiki/Augmented_triangular_prism">Augmented triangular prism</a>. %H A384139 Wikipedia, <a href="https://en.wikipedia.org/wiki/Elongated_triangular_bipyramid">Elongated triangular bipyramid</a>. %F A384139 Equals (2*sqrt(2) + 3*sqrt(3))/12 = (A010466 + A010482)/12. %F A384139 Equals the largest root of 20736*x^4 - 10080*x^2 + 361. %e A384139 0.66871496228773516484880970607808443816397995934875... %t A384139 First[RealDigits[(Sqrt[8] + Sqrt[27])/12, 10, 100]] (* or *) %t A384139 First[RealDigits[PolyhedronData["J14", "Volume"], 10, 100]] %Y A384139 Cf. A165663 (surface area - 2). %Y A384139 Cf. A010482, A010482, A383852, A384138, A384140. %K A384139 nonn,cons,easy %O A384139 0,1 %A A384139 _Paolo Xausa_, May 20 2025