A384141 Decimal expansion of the surface area of an elongated pentagonal bipyramid with unit edge.

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

Offset

1,1

Comments

The elongated pentagonal bipyramid is Johnson solid J_16.

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Wikipedia, Elongated pentagonal bipyramid.

Formula

Equals 5*(2 + sqrt(3))/2 = 5*(2 + A002194)/2.

Equals the largest root of 4*x^2 - 40*x + 25.

Equals 10*A019884^2. - R. J. Mathar, Sep 05 2025

Example

9.3301270189221932338186158537646809173570131345...

Mathematica

First[RealDigits[5*(2 + Sqrt[3])/2, 10, 100]] (* or *)
First[RealDigits[PolyhedronData["J16", "SurfaceArea"], 10, 100]]

Crossrefs

Cf. A384140 (volume).

Cf. A002163.

Essentially the same as A120011.

Sequence in context: A019721 A265162 A259837 * A215189 A201320 A212436

Adjacent sequences: A384138 A384139 A384140 * A384142 A384143 A384144

Keyword

nonn,cons,easy

Author

Paolo Xausa, May 20 2025

Status

approved