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 A380701 #7 Jan 30 2025 17:43:59 %S A380701 1,9,7,0,2,2,1,5,6,6,6,7,5,4,9,1,3,1,9,2,2,7,1,2,8,3,0,6,3,2,4,4,6,7, %T A380701 3,5,1,7,9,6,4,4,7,2,6,5,0,3,1,8,2,2,8,1,5,6,7,3,8,2,5,9,3,7,8,6,5,2, %U A380701 8,6,5,6,2,0,1,9,7,2,8,3,2,0,9,8,4,0,2,9,5,5 %N A380701 Decimal expansion of the obtuse vertex angle, in radians, in a triakis tetrahedron face. %H A380701 Paolo Xausa, <a href="/A380701/b380701.txt">Table of n, a(n) for n = 1..10000</a> %H A380701 Wikipedia, <a href="https://en.wikipedia.org/wiki/Triakis_tetrahedron">Triakis tetrahedron</a>. %F A380701 Equals arccos(-7/18). %F A380701 Equals Pi - 2*A380700. %e A380701 1.9702215666754913192271283063244673517964472650318... %t A380701 First[RealDigits[ArcCos[-7/18], 10, 100]] %Y A380701 Cf. A380700 (face acute angles). %Y A380701 Cf. A378204, A378205, A378206, A378207, A378208. %K A380701 nonn,cons,easy %O A380701 1,2 %A A380701 _Paolo Xausa_, Jan 30 2025