A377795 Decimal expansion of the midradius of a (small) rhombicosidodecahedron with unit edge length.

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

Offset

1,1

Links

Table of n, a(n) for n=1..90.

Polytope Wiki, Small rhombicosidodecahedron.

Eric Weisstein's World of Mathematics, Small Rhombicosidodecahedron.

Wikipedia, Rhombicosidodecahedron.

Index entries for algebraic numbers, degree 4.

Formula

Equals sqrt(5/2 + sqrt(5)) = sqrt(5/2 + A002163).

Minimal polynomial: 4*x^4 - 20*x^2 + 5. - Amiram Eldar, Jun 10 2026

Example

2.1762508994828215111000528659977678801980731915893...

Mathematica

First[RealDigits[Sqrt[5/2 + Sqrt[5]], 10, 100]]
(* Alternative: *)
First[RealDigits[PolyhedronData["Rhombicosidodecahedron", "Midradius"], 10, 100]]

Crossrefs

Cf. A344149 (surface area), A185093 (volume), A179592 (circumradius), A377606 (Dehn invariant, negated).

Cf. A002163.

Sequence in context: A135895 A039814 A178120 * A180568 A373050 A248950

Adjacent sequences: A377792 A377793 A377794 * A377796 A377797 A377798

Keyword

nonn,cons,easy

Author

Paolo Xausa, Nov 08 2024

Status

approved