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A380794 Decimal expansion of the obtuse vertex angle, in radians, in a triakis icosahedron face.

%I A380794 #6 Feb 05 2025 09:23:22
%S A380794 2,0,7,7,6,2,8,6,1,2,1,0,5,8,6,1,0,4,7,1,8,4,2,2,6,2,6,0,6,9,4,8,5,3,
%T A380794 0,0,7,6,6,8,7,8,6,6,4,1,0,9,6,6,9,1,5,8,0,0,0,3,7,6,7,2,4,4,6,0,4,3,
%U A380794 6,1,7,9,4,4,9,4,5,0,0,9,9,0,2,3,7,9,2,3,9,7
%N A380794 Decimal expansion of the obtuse vertex angle, in radians, in a triakis icosahedron face.
%C A380794 A triakis icosahedron face is an isoscele triangle with two acute angles (A380793) and one obtuse angle (this constant).
%H A380794 Paolo Xausa, <a href="/A380794/b380794.txt">Table of n, a(n) for n = 1..10000</a>
%H A380794 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TriakisIcosahedron.html">Triakis Icosahedron</a>.
%H A380794 Wikipedia, <a href="https://en.wikipedia.org/wiki/Triakis_icosahedron">Triakis icosahedron</a>.
%F A380794 Equals arccos(-3*A001622/10).
%F A380794 Equals Pi - 2*A380793.
%e A380794 2.077628612105861047184226260694853007668786641...
%t A380794 First[RealDigits[ArcCos[-3*GoldenRatio/10], 10, 100]]
%Y A380794 Cf. A001622, A378973, A378974, A378976, A378977, A380793.
%K A380794 nonn,cons,easy
%O A380794 1,1
%A A380794 _Paolo Xausa_, Feb 04 2025