A339259 Decimal expansion of the volume of the regular icosahedron inscribed in the unit sphere.

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

Offset: 1

Author

Hugo Pfoertner, Nov 29 2020

Keywords

• nonn
• cons

Examples

			2.536150710120409525643838222345019049081863024335333926526148385147...
		

Links

• Index entries for algebraic numbers, degree 4.

Crossrefs

Cf. A001622, A019881, A102208.

Cf. A118273 (cube), A122553 (regular octahedron), A363437 (regular tetrahedron), A363438 (regular dodecahedron).

Programs

Mathematica

RealDigits[4 * Sqrt[GoldenRatio + 2]/3, 10, 120][[1]] (* Amiram Eldar, Jun 02 2023 *)

PARI

4/3*sqrt(2+(1+sqrt(5))/2)

Formula

Equals 4*sqrt(2 + phi)/3 where phi = A001622.

Equals A102208 / A019881 ^ 3. - Amiram Eldar, Jun 02 2023