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A237603
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Decimal expansion of the inscribed sphere radius in a regular dodecahedron with unit edge.
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7
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1, 1, 1, 3, 5, 1, 6, 3, 6, 4, 4, 1, 1, 6, 0, 6, 7, 3, 5, 1, 9, 4, 3, 7, 5, 0, 3, 9, 4, 8, 6, 9, 4, 9, 3, 7, 5, 8, 8, 3, 1, 5, 0, 3, 6, 9, 8, 8, 6, 4, 8, 7, 7, 7, 2, 6, 0, 1, 2, 0, 8, 0, 0, 3, 9, 9, 8, 4, 8, 9, 6, 2, 0, 5, 6, 5, 5, 6, 5, 9, 7, 5, 8, 8
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OFFSET
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1,4
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COMMENTS
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Equals phi^2/(2*xi), where phi is the golden ratio (A001622, 2*cos(Pi/5)) and xi is its associate (A182007, 2*sin(Pi/5)).
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LINKS
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FORMULA
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EXAMPLE
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1.1135163644116067351943750394869493758831503698864877726012080...
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MATHEMATICA
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RealDigits[ Cos[Pi/5]^2 / Sin[Pi/5], 10, 111][[1]] (* Or *)
RealDigits[ Sqrt[5/8 + 11/(8 Sqrt[5])], 10, 111][[1]] (* Robert G. Wilson v, Feb 28 2014 *)
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PROG
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(PARI) sqrt(250+110*sqrt(5))/20
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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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