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 A380776 #6 Feb 03 2025 14:12:23 %S A380776 1,4,0,9,3,8,3,0,7,8,0,3,2,0,2,8,9,9,2,6,9,5,1,5,6,0,5,6,9,4,0,5,3,0, %T A380776 5,1,4,1,4,2,0,4,7,7,6,2,0,2,3,1,9,5,2,6,7,0,8,5,7,8,5,5,1,4,6,3,6,5, %U A380776 7,6,9,8,3,1,0,2,8,7,9,7,1,3,3,2,4,0,9,6,3,9 %N A380776 Decimal expansion of the acute vertex angle, in radians, in a pentagonal icositetrahedron face. %C A380776 A pentagonal icositetrahedron face is an irregular pentagon with one acute angle (this constant) and four (equal) obtuse angles (A380777). %H A380776 Paolo Xausa, <a href="/A380776/b380776.txt">Table of n, a(n) for n = 1..10000</a> %H A380776 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PentagonalIcositetrahedron.html">Pentagonal Icositetrahedron</a>. %H A380776 Wikipedia, <a href="https://en.wikipedia.org/wiki/Pentagonal_icositetrahedron">Pentagonal icositetrahedron</a>. %F A380776 Equals arccos(2 - A058265). %F A380776 Equals arccos(c), where c is the real root of x^3 - 5*x^2 + 7*x - 1. %F A380776 Equals 3*Pi - 4*A380777. %e A380776 1.409383078032028992695156056940530514142047762023... %t A380776 First[RealDigits[ArcCos[Root[#^3 - 5*#^2 + 7*# - 1 &, 1]], 10, 100]] %Y A380776 Cf. A058265, A378823, A378824, A378825, A378826, A378827, A380775, A380777. %K A380776 nonn,cons,easy %O A380776 1,2 %A A380776 _Paolo Xausa_, Feb 03 2025