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 A384140 #8 May 22 2025 05:21:24 %S A384140 2,3,2,3,4,8,3,0,6,5,3,8,0,6,1,6,0,6,4,1,2,6,4,4,3,1,1,6,4,4,9,5,4,9, %T A384140 2,8,5,6,9,4,0,9,2,3,6,6,6,4,4,4,9,2,1,3,9,5,6,3,0,0,2,8,1,0,8,0,8,0, %U A384140 7,9,0,6,9,3,4,5,4,4,9,9,7,2,9,5,0,3,0,9,1,0 %N A384140 Decimal expansion of the volume of an elongated pentagonal bipyramid with unit edge. %C A384140 The elongated pentagonal bipyramid is Johnson solid J_16. %H A384140 Paolo Xausa, <a href="/A384140/b384140.txt">Table of n, a(n) for n = 1..10000</a> %H A384140 Wikipedia, <a href="https://en.wikipedia.org/wiki/Elongated_pentagonal_bipyramid">Elongated pentagonal bipyramid</a>. %F A384140 Equals (5 + sqrt(5) + 3*sqrt(25 + 10*sqrt(5)))/12 = (5 + A002163 + 3*sqrt(25 + 10*A002163))/12. %F A384140 Equals the largest root of 20736*x^4 - 34560*x^3 - 44640*x^2 + 27600*x + 6025. %e A384140 2.32348306538061606412644311644954928569409236664... %t A384140 First[RealDigits[(5 + Sqrt[5] + 3*Sqrt[25 + 10*Sqrt[5]])/12, 10, 100]] (* or *) %t A384140 First[RealDigits[PolyhedronData["J16", "Volume"], 10, 100]] %Y A384140 Cf. A384141 (surface area). %Y A384140 Cf. A002163, A383852, A384138, A384139. %K A384140 nonn,cons,easy %O A384140 1,1 %A A384140 _Paolo Xausa_, May 20 2025