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A012997
Expansion of e.g.f.: exp(arctan(x)+tan(x))=1+2*x+4/2!*x^2+8/3!*x^3+16/4!*x^4+72/5!*x^5...
0
1, 2, 4, 8, 16, 72, 544, 3040, 11008, 64896, 1060224, 10595840, 38065152, 87854080, 9708670976, 170663275520, 276991311872, -13108265091072, 283899182678016, 9548887177330688, -9456062364418048
OFFSET
0,2
MATHEMATICA
With[{nn=20}, CoefficientList[Series[Exp[ArcTan[x]+Tan[x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Jul 07 2019 *)
CROSSREFS
Sequence in context: A230863 A322037 A013133 * A013184 A066713 A004000
KEYWORD
sign
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
Definition clarified by Harvey P. Dale, Jul 07 2019
STATUS
approved