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A104955
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Decimal expansion of the area of the regular 5-gon (pentagon) of circumradius = 1.
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3
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2, 3, 7, 7, 6, 4, 1, 2, 9, 0, 7, 3, 7, 8, 8, 3, 9, 3, 0, 2, 9, 1, 0, 9, 8, 3, 3, 3, 4, 4, 8, 4, 5, 5, 3, 5, 8, 5, 1, 4, 2, 4, 6, 5, 8, 5, 3, 1, 4, 3, 7, 5, 5, 5, 6, 1, 1, 8, 2, 6, 4, 1, 1, 1, 0, 7, 5, 3, 8, 2, 9, 2, 5, 2, 1, 2, 9, 8, 3, 7, 5, 4, 2, 9, 6, 9, 8, 2, 0, 2, 7, 4, 2, 7, 0, 2, 8, 4, 5, 4, 1, 8, 9, 7, 4
(list; constant; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Equivalently, the area in the complex plane of the smallest convex set containing all order-5 roots of unity.
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LINKS
| Eric Weisstein et al., "Root of Unity."
Eric Weisstein's World of Mathematics, "de Moivre Number."
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FORMULA
| (5*Sqrt[(5 + Sqrt[5])/2])/4
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EXAMPLE
| 2.3776412907378839302910983334484553585142465853143755561182641110753829252129837542969820274270284541897492938785075105224676655...
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MATHEMATICA
| Floor[n/2]*Sin[(2*Pi)/n] - Sin[(4*Pi*Floor[n/2])/n]/2 /. n -> 5
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CROSSREFS
| Cf. A104954, A104956, A104957.
Sequence in context: A070964 A111075 A011372 * A011161 A171464 A179894
Adjacent sequences: A104952 A104953 A104954 * A104956 A104957 A104958
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KEYWORD
| nonn,cons
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AUTHOR
| Joseph Biberstine (jrbibers(AT)indiana.edu), Mar 30 2005
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