A380862 - OEIS

%I #11 Feb 08 2025 03:43:47

%S 1,5,1,7,9,8,5,3,7,7,4,6,0,2,1,5,4,6,3,6,0,2,1,9,1,3,5,7,3,8,6,0,7,2,

%T 4,4,8,1,7,1,2,3,3,3,8,2,5,2,7,1,6,7,2,3,0,1,0,8,0,7,6,0,2,2,4,5,5,8,

%U 8,5,1,8,3,5,3,0,5,5,1,6,4,4,8,8,2,5,1,1,8,9

%N Decimal expansion of the largest acute angles, in radians, in a deltoidal hexecontahedron face.

%C A deltoidal hexecontahedron face is a kite with one smallest acute angle (A380861), two largest acute angles (this constant) and one obtuse angle (A380863).

%H Paolo Xausa, <a href="/A380862/b380862.txt">Table of n, a(n) for n = 1..10000</a>

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Deltoidal_hexecontahedron">Deltoidal hexecontahedron</a>.

%F Equals arccos(1/2 - 1/sqrt(5)) = arccos(1/2 - A020762).

%F Equals (2*Pi - A380861 - A380863)/2.

%e 1.517985377460215463602191357386072448171233382527...

%t First[RealDigits[ArcCos[1/2 - 1/Sqrt[5]], 10, 100]]

%Y Cf. A020762, A379385, A379386, A379387, A379388, A379389, A380861, A380863.

%K nonn,cons,easy,new

%O 1,2

%A _Paolo Xausa_, Feb 06 2025