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Search: id:A101923
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| A101923 |
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Expansion of 2 * arccot(cos(x)). |
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+0
2
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| 1, 2, 1, 148, 3719, 20098, 5055961, 403644152, 7831409041, 2707151879398, 472143935754479, 22085804322342748, 9362259685093715401, 2995219209329323622102, 274269338931958691728681
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OFFSET
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1,2
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COMMENT
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Odd coefficients are zero.
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FORMULA
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2acot(cos(x)) = Pi/2 + x^2/2! + 2*x^4/4! + x^6/6! + 148*x^8/8! + 3719*x^10/10! +...
2atan(cos(x)) = Pi/2 - x^2/2! - 2*x^4/4! - x^6/6! + 148*x^8/8! + 3719*x^10/10! +...
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CROSSREFS
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Cf. A012494.
Sequence in context: A039923 A081708 A012004 this_sequence A010788 A016448 A098879
Adjacent sequences: A101920 A101921 A101922 this_sequence A101924 A101925 A101926
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KEYWORD
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nonn
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AUTHOR
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Ralf Stephan, Dec 27 2004
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