A386411 Decimal expansion of the volume of an augmented truncated tetrahedron with unit edge.

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

Offset: 1

Author

Paolo Xausa, Jul 21 2025

Keywords

• nonn
• cons
• easy

Comments

The augmented truncated tetrahedron is Johnson solid J_65.

Examples

			3.889087296526011384204643991576669716066597657...
		

Links

• Paolo Xausa, Table of n, a(n) for n = 1..10000
• Wikipedia, Augmented truncated tetrahedron.

Crossrefs

Cf. A386412 (surface area).

Cf. A010466, A020829, A377275.

Programs

Mathematica

First[RealDigits[11/Sqrt[8], 10, 100]] (* or *)
First[RealDigits[PolyhedronData["J65", "Volume"], 10, 100]]

Formula

Equals 11/(2*sqrt(2)) = 11/A010466.

Equals A377275 + 10*A020829.

Equals the largest root of 8*x^2 - 121.