A383852 Decimal expansion of the volume of an elongated triangular pyramid with unit edge.

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

Offset: 0

Author

Paolo Xausa, May 19 2025

Keywords

• nonn
• cons
• easy

Comments

The elongated triangular pyramid is Johnson solid J_7.

Examples

			0.55086383208997724411533564572727626494984063640067...
		

Links

• Paolo Xausa, Table of n, a(n) for n = 0..10000
• Wikipedia, Elongated triangular pyramid.

Crossrefs

Cf. A165663 (surface area).

Cf. A002193, A010482.

Programs

Mathematica

First[RealDigits[(Sqrt[2] + Sqrt[27])/12, 10, 100]] (* or *)
First[RealDigits[PolyhedronData["J7", "Volume"], 10, 100]]

Formula

Equals (sqrt(2) + 3*sqrt(3))/12 = (A002193 + A010482)/12.

Minimal polynomial: 20736*x^4 - 8352*x^2 + 625. - Stefano Spezia, May 19 2025