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 A378394 #10 Feb 11 2025 09:58:56 %S A378394 2,4,1,0,6,1,3,1,4,1,6,5,3,4,0,7,6,0,6,1,5,3,6,6,5,7,8,5,4,6,5,9,4,9, %T A378394 1,8,5,9,8,0,3,6,2,9,0,6,0,8,9,5,9,1,9,8,3,5,2,1,7,8,6,7,1,8,7,8,5,0, %U A378394 3,5,1,5,8,3,3,7,2,6,7,4,1,9,4,7,8,5,0,5,5,6 %N A378394 Decimal expansion of the dihedral angle, in radians, between any two adjacent faces in a deltoidal icositetrahedron. %C A378394 The deltoidal icositetrahedron is the dual polyhedron of the (small) rhombicuboctahedron. %H A378394 Paolo Xausa, <a href="/A378394/b378394.txt">Table of n, a(n) for n = 1..10000</a> %H A378394 Wikipedia, <a href="https://en.wikipedia.org/wiki/Deltoidal_icositetrahedron">Deltoidal icositetrahedron</a>. %H A378394 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>. %F A378394 Equals arcsec(4*sqrt(2) - 7) = arcsec(A010487 - 7). %F A378394 Equals arccos(-(4*sqrt(2) + 7)/17) = arccos(-(A010487 + 7)/17). %e A378394 2.410613141653407606153665785465949185980362906... %t A378394 First[RealDigits[ArcSec[Sqrt[32] - 7], 10, 100]] (* or *) %t A378394 First[RealDigits[First[PolyhedronData["DeltoidalIcositetrahedron", "DihedralAngles"]], 10, 100]] %o A378394 (PARI) acos(-(4*sqrt(2) + 7)/17) \\ _Charles R Greathouse IV_, Feb 11 2025 %Y A378394 Cf. A378390 (surface area), A378391 (volume), A378392 (inradius), A378393 (midradius). %Y A378394 Cf. A177870 and A195702 (dihedral angles of a (small) rhombicuboctahedron). %K A378394 nonn,cons,easy %O A378394 1,1 %A A378394 _Paolo Xausa_, Nov 30 2024