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 A012004 arcsinh(log(cos(x)))=-1/2!*x^2-2/4!*x^4-1/6!*x^6+148/8!*x^8-61/10!*x^10... 1
 0, -1, -2, -1, 148, -61, -395702, -28299181, 93652648, 265509939239, 14066899733398, -8605652824527001, -2442549938212838852, 25891773268121861099, 210295085697229695516898 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Vaclav Kotesovec, Table of n, a(n) for n = 0..200 FORMULA Lim sup n->infinity (|a(n)|/(2*n)!)^(1/n) = 1/(arccos(cos(1/2) - sin(1/2))^2 + arccosh(cos(1/2) + sin(1/2))^2) = 0.494130490883618452622838693... . - Vaclav Kotesovec, Mar 21 2016 MATHEMATICA nmax = 20; Table[(CoefficientList[Series[ArcSinh[Log[Cos[x]]], {x, 0, 2*nmax}], x] * Range[0, 2*nmax]!)[[2*n+1]], {n, 0, nmax}] (* Vaclav Kotesovec, Mar 21 2016 *) CROSSREFS Sequence in context: A335600 A039923 A081708 * A101923 A010788 A258819 Adjacent sequences:  A012001 A012002 A012003 * A012005 A012006 A012007 KEYWORD sign AUTHOR Patrick Demichel (patrick.demichel(AT)hp.com) EXTENSIONS Prepended a(0)=0 from Vaclav Kotesovec, Mar 21 2016 STATUS approved

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Last modified December 8 17:01 EST 2021. Contains 349596 sequences. (Running on oeis4.)