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 A385260 #8 Jun 29 2025 09:04:33 %S A385260 1,1,3,9,7,3,7,8,5,1,2,2,1,3,3,8,1,1,2,4,0,8,9,4,3,3,0,9,3,5,0,5,6,8, %T A385260 0,2,1,2,4,4,6,8,7,9,5,0,3,6,7,8,0,2,3,9,7,4,9,9,4,9,0,7,2,8,8,7,7,7, %U A385260 4,4,7,4,8,9,1,5,3,4,2,3,4,7,3,3,0,5,5,6,5,7 %N A385260 Decimal expansion of the volume of a gyroelongated pentagonal bicupola with unit edge. %C A385260 The gyroelongated pentagonal bicupola is Johnson solid J_46. %H A385260 Paolo Xausa, <a href="/A385260/b385260.txt">Table of n, a(n) for n = 2..10000</a> %H A385260 Wikipedia, <a href="https://en.wikipedia.org/wiki/Gyroelongated_pentagonal_bicupola">Gyroelongated pentagonal bicupola</a>. %F A385260 Equals (10 + 8*sqrt(5) + 5*sqrt(2*(sqrt(650 + 290*sqrt(5)) - sqrt(5) - 1)))/6 = (10 + 8*A002163 + 5*sqrt(2*(sqrt(650 + 290*A002163) - A002163 - 1)))/6. %F A385260 Equals the largest real root of 6561*x^8 - 87480*x^7 + 313470*x^6 + 753300*x^5 - 22424850*x^4 - 84591000*x^3 - 85909500*x^2 + 8715000*x + 35547500. %e A385260 11.397378512213381124089433093505680212446879503678... %t A385260 First[RealDigits[(10 + 8*# + 5*Sqrt[2*(Sqrt[650 + 290*#] - # - 1)])/6 & [Sqrt[5]], 10, 100]] (* or *) %t A385260 First[RealDigits[PolyhedronData["J46", "Volume"], 10, 100]] %Y A385260 Cf. A385261 (surface area). %Y A385260 Cf. A002163, A384283, A385256, A385258. %K A385260 nonn,cons,easy %O A385260 2,3 %A A385260 _Paolo Xausa_, Jun 27 2025