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 A380002 #9 Jan 13 2025 04:12:57 %S A380002 1,7,4,9,8,5,2,5,6,6,7,3,6,2,0,2,7,9,1,6,7,6,4,4,6,6,9,3,6,5,5,9,2,1, %T A380002 1,7,9,6,4,9,8,1,5,8,1,8,5,9,0,3,7,6,0,0,4,3,8,7,8,6,1,2,6,9,7,0,3,9, %U A380002 8,2,5,2,6,6,0,8,4,0,1,4,5,1,4,1,4,9,0,4,5,7 %N A380002 Decimal expansion of long/short edge length ratio of a pentagonal hexecontahedron. %H A380002 Paolo Xausa, <a href="/A380002/b380002.txt">Table of n, a(n) for n = 1..10000</a> %H A380002 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PentagonalHexecontahedron.html">Pentagonal Hexecontahedron</a>. %H A380002 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentagonal_hexecontahedron">Pentagonal hexecontahedron</a>. %F A380002 Equals (1 + xi)/(2 - xi^2), where xi = A377849. %F A380002 Equals the largest real root of 31*x^6 - 122*x^5 + 177*x^4 - 128*x^3 + 51*x^2 - 11*x + 1. %e A380002 1.749852566736202791676446693655921179649815818590... %t A380002 First[RealDigits[(1 + #)/(2 - #^2) & [Root[#^3 + 2*#^2 - GoldenRatio^2 &, 1]], 10, 100]] (* or *) %t A380002 First[RealDigits[1/Divide @@ PolyhedronData["PentagonalHexecontahedron", "EdgeLengths"], 10, 100]] %Y A380002 Cf. A379888 (surface area), A379889 (volume), A379890 (inradius), A379890 (midradius), A379892 (dihedral angle), A380003 and A380004 (face internal angles). %Y A380002 Cf. A377849. %K A380002 nonn,cons,easy %O A380002 1,2 %A A380002 _Paolo Xausa_, Jan 11 2025