A013440 Expansion of e.g.f.: exp(tan(x)-arctan(x))=1+4/3!*x^3-8/5!*x^5+160/6!*x^6+992/7!*x^7...

1, 0, 0, 4, 0, -8, 160, 992, -1792, -14464, 484224, 3391232, -30840832, -175044608, 7718963200, 53080130560, -1315838558208, -6862446264320, 426971596029952, 2514483259473920, -136067874243248128

Offset

0,4

Links

Table of n, a(n) for n=0..20.

Maple

A013440 := proc(n)
        exp(tan(x)-arctan(x)) ;
        coeftayl( %, x=0, n) ;
        %*n! ;
end proc: # R. J. Mathar, Dec 16 2011

Mathematica

With[{nn=20}, CoefficientList[Series[Exp[Tan[x]-ArcTan[x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Aug 12 2015 *)

Crossrefs

Sequence in context: A214202 A019249 A260491 * A013496 A187172 A296570

Adjacent sequences: A013437 A013438 A013439 * A013441 A013442 A013443

Keyword

sign

Author

Patrick Demichel (patrick.demichel(AT)hp.com)

Extensions

Definition clarified by Harvey P. Dale, Aug 12 2015

Status

approved