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 A009698 Expansion of tan(tan(x))*sin(x). 1
 0, 2, 12, 358, 19352, 1709194, 222722596, 40122780142, 9543330683696, 2895895566420498, 1091590070839432764, 500335689476146083190, 274027979513688992336584, 176734166480671985581245594 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS FORMULA a(n) ~ (2*n)! * 8 * Pi / ((4+Pi^2)^(3/2) * arctan(Pi/2)^(2*n+1)). - Vaclav Kotesovec, Jan 23 2015 MATHEMATICA Tan[ Tan[ x ] ]*Sin[ x ] (* Even Part *) nn = 20; Table[(CoefficientList[Series[Sin[x]*Tan[Tan[x]], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Jan 23 2015 *) CROSSREFS Sequence in context: A192892 A105231 A009398 * A012724 A012624 A061307 Adjacent sequences:  A009695 A009696 A009697 * A009699 A009700 A009701 KEYWORD nonn AUTHOR EXTENSIONS Extended and signs tested Mar 15 1997 by Olivier Gérard. STATUS approved

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Last modified October 16 06:04 EDT 2019. Contains 328046 sequences. (Running on oeis4.)