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 A003719 Expansion of tan(x)*cosh(x). (Formerly M3996) 4
 1, 5, 41, 685, 19921, 887765, 56126201, 4776869245, 526589630881, 72989204937125, 12424192360405961, 2547879762929443405, 619570064016825283441, 176273806836039238900085, 58010159408189457446855321, 21864887814006548202566779165 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS FORMULA a(n) = Sum_{k>=0} binomial(2n+1, 2k)*A000111(2n+1-2k). - Philippe Deléham, Aug 27 2005 a(n) ~ cosh(Pi/2) * (2*n+1)! * 2^(2*n+3) / Pi^(2*n+2). - Vaclav Kotesovec, Feb 16 2015 MATHEMATICA nn = 20; Table[(CoefficientList[Series[Cosh[x]*Tan[x], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Feb 16 2015 *) CROSSREFS Bisection of A009739 and (apparently) A062272. Sequence in context: A100288 A076094 A076131 * A181033 A189997 A197173 Adjacent sequences:  A003716 A003717 A003718 * A003720 A003721 A003722 KEYWORD nonn AUTHOR EXTENSIONS Extended and formatted Mar 15 1997 by Olivier Gérard Prior Mathematica program deleted by Harvey P. Dale, Nov 04 2019 STATUS approved

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Last modified August 11 06:25 EDT 2020. Contains 336422 sequences. (Running on oeis4.)