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 A384143 #9 May 23 2025 10:14:16 %S A384143 3,7,7,6,5,8,7,5,1,3,3,3,0,8,9,5,1,4,7,6,2,5,9,1,0,1,1,5,7,6,6,8,9,0, %T A384143 2,8,2,5,5,5,6,0,1,1,1,0,1,9,6,3,6,1,0,0,3,0,6,4,2,7,6,9,1,7,5,0,3,5, %U A384143 0,9,9,2,4,0,8,1,6,2,2,5,8,7,9,9,7,0,4,2,2,2 %N A384143 Decimal expansion of the volume of an elongated triangular cupola with unit edge. %C A384143 The elongated triangular cupola is Johnson solid J_18. %H A384143 Paolo Xausa, <a href="/A384143/b384143.txt">Table of n, a(n) for n = 1..10000</a> %H A384143 Wikipedia, <a href="https://en.wikipedia.org/wiki/Elongated_triangular_cupola">Elongated triangular cupola</a>. %F A384143 Equals (5*sqrt(2) + 9*sqrt(3))/6 = (5*A002193 + 9*A002194)/6. %F A384143 Equals the largest root of 1296*x^4 - 21096*x^2 + 37249. %e A384143 3.776587513330895147625910115766890282555601110196... %t A384143 First[RealDigits[(5*Sqrt[2] + 9*Sqrt[3])/6, 10, 100]] (* or *) %t A384143 First[RealDigits[PolyhedronData["J18", "Volume"], 10, 100]] %Y A384143 Cf. A384141 (surface area - 4). %Y A384143 Cf. A002193, A002194, A344078, A383852, A384139. %K A384143 nonn,cons,easy %O A384143 1,1 %A A384143 _Paolo Xausa_, May 22 2025