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 A012804 tan(sec(x)*arctan(x))=x+3/3!*x^3+65/5!*x^5+2051/7!*x^7+154209/9!*x^9... 1
 1, 3, 65, 2051, 154209, 14263139, 2239618017, 411001918627, 110281957937729, 33549045899804227, 13741520797366881025, 6244634409478025568963, 3628509505783902549611425, 2300839492251656581442561187 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Note that a(131) is negative!. - Vaclav Kotesovec, Feb 07 2015 LINKS Vaclav Kotesovec, Table of n, a(n) for n = 0..200 MATHEMATICA nn = 20; Table[(CoefficientList[Series[Tan[ArcTan[x]*Sec[x]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Feb 07 2015 *) CROSSREFS Sequence in context: A112000 A216859 A346162 * A348084 A012837 A036778 Adjacent sequences: A012801 A012802 A012803 * A012805 A012806 A012807 KEYWORD sign AUTHOR Patrick Demichel (patrick.demichel(AT)hp.com) STATUS approved

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Last modified September 18 23:40 EDT 2024. Contains 376002 sequences. (Running on oeis4.)