A377752 Decimal expansion of the circumradius of a truncated icosahedron with unit edge length.

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

Offset: 1

Author

Paolo Xausa, Nov 07 2024

Keywords

• nonn
• cons
• easy

Examples

			2.47801865906761553756640791226630780693649473...
		

Links

• Eric Weisstein's World of Mathematics, Truncated Icosahedron.
• Wikipedia, Truncated icosahedron.
• Index entries for algebraic numbers, degree 4.

Crossrefs

Cf. A377750 (surface area), A377751 (volume), A205769 (midradius + 1), A377787 (Dehn invariant).

Cf. A019881 (analogous for a regular icosahedron).

Cf. A002163.

Programs

Mathematica

First[RealDigits[Sqrt[58 + 18*Sqrt[5]]/4, 10, 100]] (* or *)
First[RealDigits[PolyhedronData["TruncatedIcosahedron", "Circumradius"], 10, 100]]

PARI

sqrt(58 + 18*sqrt(5))/4 \\ Charles R Greathouse IV, Feb 05 2025

Formula

Equals sqrt(58 + 18*sqrt(5))/4 = sqrt(58 + 18*A002163)/4.