A384287 Decimal expansion of the volume of a square orthobicupola with unit edge.

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

Offset

1,1

Comments

The square orthobicupola is Johnson solid J_28.

Also the volume of a square gyrobicupola (Johnson solid J_29) with unit edge.

Links

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

Wikipedia, Square gyrobicupola.

Wikipedia, Square orthobicupola.

Formula

Equals 2 + (4/3)*sqrt(2) = 2 + (4/3)*A002193 = 2 + A010487/3.

Equals the largest root of 9*x^2 - 36*x + 4.

Example

3.885618083164126731735584965612930771426229167169...

Mathematica

First[RealDigits[2 + Sqrt[32]/3, 10, 100]] (* or *)
First[RealDigits[PolyhedronData["J28", "Volume"], 10, 100]]

Crossrefs

Cf. A010469 (surface area - 10).

Cf. A002193, A010487, A384624.

Sequence in context: A118817 A386736 A179553 * A157471 A288094 A131596

Adjacent sequences: A384284 A384285 A384286 * A384288 A384289 A384290

Keyword

nonn,cons,easy

Author

Paolo Xausa, Jun 05 2025

Status

approved