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 A386740 #7 Aug 01 2025 09:20:56 %S A386740 1,7,5,1,0,5,3,9,0,0,3,7,1,9,2,2,4,0,1,1,9,5,4,2,7,4,3,3,1,7,3,4,2,9, %T A386740 2,5,1,2,5,1,1,4,8,1,5,2,7,0,4,9,5,2,2,7,8,9,5,6,0,1,7,9,2,0,1,7,5,4, %U A386740 3,1,3,5,0,3,8,8,0,1,3,8,1,4,4,6,5,9,8,8,2,4 %N A386740 Decimal expansion of the volume of an augmented sphenocorona with unit edges. %C A386740 The augmented sphenocorona is Johnson solid J_87. %H A386740 Paolo Xausa, <a href="/A386740/b386740.txt">Table of n, a(n) for n = 1..10000</a> %H A386740 Wikipedia, <a href="https://en.wikipedia.org/wiki/Augmented_sphenocorona">Augmented sphenocorona</a>. %F A386740 Equals sqrt(1 + 3*sqrt(3/2) + sqrt(13 + 3*sqrt(6)))/2 + 1/(3*sqrt(2)) = sqrt(1 + 3*A115754 + sqrt(13 + A010507))/2 + A020775. %F A386740 Equals A386739 + A020775. %F A386740 Equals the largest real root of 45137758519296*x^16 - 110336743047168*x^14 - 191069246324736*x^12 + 209269081571328*x^10 + 364547659290624*x^8 - 58793017190400*x^6 + 3306865979520*x^4 - 1275399855936*x^2 + 1439671249. %e A386740 1.7510539003719224011954274331734292512511481527... %t A386740 First[RealDigits[Sqrt[1 + 3*Sqrt[3/2] + Sqrt[13 + Sqrt[54]]]/2 + 1/Sqrt[18], 10, 100]] (* or *) %t A386740 First[RealDigits[PolyhedronData["J87", "Volume"], 10, 100]] %Y A386740 Cf. A010502 (surface area - 1). %Y A386740 Cf. A010507, A020775, A115754, A386739, A386741. %K A386740 nonn,cons,easy %O A386740 1,2 %A A386740 _Paolo Xausa_, Aug 01 2025