1,1

An example of such a cone is the one circumscribed to a cube from one of its vertices. When expressed as a fraction of the full solid angle, this constant leads to A156309.

Stanislav Sykora, Table of n, a(n) for n = 1..2000

Equals 2*Pi*(1-sqrt(1/3)) = 4*Pi*A156309 = 2*Pi*(1-cos(A210974)).

2.65558657871115077573713025127469430382620630256473049081011931...

First@RealDigits@N[2*Pi*(1 - Sqrt[1/3]), 25] (* G. C. Greubel, Aug 15 2016 *)

(PARI) 2*Pi*(1-sqrt(1/3))

Cf. A000796, A156309, A195696, A210974.

Sequence in context: A198821 A171897 A105029 * A190124 A067548 A245698

Adjacent sequences: A273618 A273619 A273620 * A273622 A273623 A273624

nonn,cons

Stanislav Sykora, Aug 15 2016

approved