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URL: https://oeis.org/A385260

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A385260
Decimal expansion of the volume of a gyroelongated pentagonal bicupola with unit edge.
7
1, 1, 3, 9, 7, 3, 7, 8, 5, 1, 2, 2, 1, 3, 3, 8, 1, 1, 2, 4, 0, 8, 9, 4, 3, 3, 0, 9, 3, 5, 0, 5, 6, 8, 0, 2, 1, 2, 4, 4, 6, 8, 7, 9, 5, 0, 3, 6, 7, 8, 0, 2, 3, 9, 7, 4, 9, 9, 4, 9, 0, 7, 2, 8, 8, 7, 7, 7, 4, 4, 7, 4, 8, 9, 1, 5, 3, 4, 2, 3, 4, 7, 3, 3, 0, 5, 5, 6, 5, 7
OFFSET
2,3
COMMENTS
The gyroelongated pentagonal bicupola is Johnson solid J_46.
FORMULA
Equals (10 + 8*sqrt(5) + 5*sqrt(2*(sqrt(650 + 290*sqrt(5)) - sqrt(5) - 1)))/6 = (10 + 8*A002163 + 5*sqrt(2*(sqrt(650 + 290*A002163) - A002163 - 1)))/6.
Equals the largest real root of 6561*x^8 - 87480*x^7 + 313470*x^6 + 753300*x^5 - 22424850*x^4 - 84591000*x^3 - 85909500*x^2 + 8715000*x + 35547500.
EXAMPLE
11.397378512213381124089433093505680212446879503678...
MATHEMATICA
First[RealDigits[(10 + 8*# + 5*Sqrt[2*(Sqrt[650 + 290*#] - # - 1)])/6 & [Sqrt[5]], 10, 100]] (* or *)
First[RealDigits[PolyhedronData["J46", "Volume"], 10, 100]]
CROSSREFS
Cf. A385261 (surface area).
Sequence in context: A343786 A254158 A193026 * A296503 A388221 A265298
KEYWORD
nonn,cons,easy
AUTHOR
Paolo Xausa, Jun 27 2025
STATUS
approved