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A350885
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Decimal expansion of 1 - 2*cotan(2).
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0
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1, 9, 1, 5, 3, 1, 5, 1, 0, 8, 7, 2, 0, 5, 7, 1, 5, 2, 7, 5, 0, 0, 5, 5, 4, 8, 2, 0, 8, 6, 4, 0, 9, 4, 5, 5, 2, 8, 5, 6, 9, 7, 2, 6, 5, 8, 4, 6, 3, 3, 4, 8, 6, 5, 9, 2, 8, 2, 7, 8, 4, 3, 2, 5, 2, 7, 2, 5, 8, 4, 5, 4, 0, 3, 1, 2, 5, 6, 2, 6, 1, 7, 3, 5, 6, 6, 1, 7, 0, 4, 5, 4, 4, 2, 0, 4, 6
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OFFSET
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1,2
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COMMENTS
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The constant given in the name is computed using a telescopic sum coming from cotan(x) - 2*cotan(2*x) = tan(x).
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REFERENCES
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J. Quinet, Cours élémentaire de Mathématiques Supérieures, Tome 3, Calcul intégral et Séries, Bordas, 1973, Exercice 7.36, pp 111 and 231.
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LINKS
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FORMULA
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Equals Sum_{m>=0} (1/2^m) * (tan(1/2^m)).
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EXAMPLE
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1.915315108720571527500554820864094552856972658463348659...
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MAPLE
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evalf(1-2/tan(2), 120);
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MATHEMATICA
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RealDigits[1 - 2*Cot[2], 10, 100][[1]] (* Amiram Eldar, Jan 21 2022 *)
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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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