A385259 Decimal expansion of the surface area of a gyroelongated square bicupola with unit edge.

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

Offset: 2

Author

Paolo Xausa, Jun 26 2025

Keywords

• nonn
• cons
• easy

Comments

The gyroelongated square bicupola is Johnson solid J_45.

Examples

			20.392304845413263761164678049035234201656831522862...
		

Links

• Paolo Xausa, Table of n, a(n) for n = 2..10000
• Wikipedia, Gyroelongated square bicupola.

Crossrefs

Cf. A385258 (volume).

Cf. A002194, A179588, A384215, A385257.

Programs

Mathematica

First[RealDigits[10 + 6*Sqrt[3], 10, 100]] (* or *)
First[RealDigits[PolyhedronData["J45", "SurfaceArea"], 10, 100]]

Formula

Equals 10 + 6*sqrt(3) = 10 + 6*A002194.

Equals the largest root of x^2 - 20*x - 8.