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 A009700 Expansion of tan(tan(x))*x. 1
 0, 2, 16, 432, 23168, 2039040, 265344000, 47773128704, 11359970459648, 3446710775119872, 1299134788619468800, 595445934379289804800, 326113437715996197519360, 210324874581761164037849088 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Table of n, a(n) for n=0..13. FORMULA a(n) ~ (2*n)! * 8 / ((4+Pi^2) * arctan(Pi/2)^(2*n)). - Vaclav Kotesovec, Jan 23 2015 MATHEMATICA With[{nn=30}, Take[CoefficientList[Series[Tan[Tan[x]]*x , {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jun 08 2014 *) CROSSREFS Sequence in context: A282309 A009397 A229023 * A358784 A012030 A012682 Adjacent sequences: A009697 A009698 A009699 * A009701 A009702 A009703 KEYWORD nonn AUTHOR R. H. Hardin EXTENSIONS Extended and signs tested Mar 15 1997 by Olivier Gérard. Previous Mathematica program replaced by Harvey P. Dale, Jun 08 2014 STATUS approved

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Last modified June 5 02:46 EDT 2023. Contains 363130 sequences. (Running on oeis4.)