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A232810
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Decimal expansion of the surface index of a regular dodecahedron.
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11
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5, 3, 1, 1, 6, 1, 3, 9, 9, 7, 0, 6, 9, 0, 8, 3, 6, 6, 9, 7, 9, 6, 6, 6, 6, 7, 0, 1, 4, 6, 1, 0, 8, 6, 3, 3, 7, 8, 0, 9, 8, 8, 8, 3, 9, 9, 3, 4, 1, 4, 9, 3, 4, 2, 2, 6, 6, 3, 7, 6, 1, 0, 1, 6, 8, 8, 4, 9, 9, 3, 1, 0, 4, 2, 6, 5, 6, 8, 1, 0, 4, 7, 7, 0, 1, 4, 4, 0, 8, 2, 4, 0, 1, 7, 9, 0, 2, 9, 1, 9, 6, 1, 8, 5, 6
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OFFSET
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1,1
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COMMENTS
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Equivalently, the surface area of a regular dodecahedron with unit volume. Among Platonic solids, surface indices decrease with increasing number of faces: A232812 (tetrahedron), 6.0 (cube = hexahedron), A232811 (octahedron), this one, and A232809 (icosahedron).
An algebraic integer with degree 12 and minimal polynomial x^12 - 18954000x^6 + 425152800000. - Charles R Greathouse IV, Apr 25 2016
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LINKS
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FORMULA
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Equals 3*sqrt(25+10*sqrt(5))/((15+7*sqrt(5))/4)^(2/3).
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EXAMPLE
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5.311613997069083669796666701461086337809888399341493422663761...
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MATHEMATICA
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RealDigits[3*Sqrt[25 + 10*Sqrt[5]]/((15 + 7*Sqrt[5])/4)^(2/3), 10, 120][[1]] (* Amiram Eldar, May 25 2023 *)
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PROG
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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