A101923 - OEIS

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A101923

Expansion of 2 * arccot(cos(x)).

1, 2, 1, 148, 3719, 20098, 5055961, 403644152, 7831409041, 2707151879398, 472143935754479, 22085804322342748, 9362259685093715401, 2995219209329323622102, 274269338931958691728681 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Odd coefficients are zero.`
	FORMULA	`2acot(cos(x)) = Pi/2 + x^2/2! + 2x^4/4! + x^6/6! + 148x^8/8! + 3719x^10/10! +...` `2atan(cos(x)) = Pi/2 - x^2/2! - 2x^4/4! - x^6/6! + 148x^8/8! + 3719x^10/10! +...`
	CROSSREFS	`Cf. A012494.` `Sequence in context: A039923 A081708 A012004 * A010788 A016448 A098879` `Adjacent sequences: A101920 A101921 A101922 * A101924 A101925 A101926`
	KEYWORD	`nonn`
	AUTHOR	`Ralf Stephan, Dec 27 2004`

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Last modified February 14 22:30 EST 2012. Contains 205678 sequences.