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A013466 sec(arctan(x)-arctanh(x))=1+160/6!*x^6+691200/10!*x^10+19712000/12!*x^12... 0
1, 0, 0, 160, 0, 691200, 19712000, 14125363200, 1476034560000, 949310881792000, 219556882022400000, 161772486589808640000, 65109683806263050240000, 58457850571785240576000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..13.

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[Sec[ArcTan[x]-ArcTanh[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Ray Chandler, Nov 29 2016 *)

CROSSREFS

Sequence in context: A013454 A013455 A013465 * A060675 A171225 A290463

Adjacent sequences:  A013463 A013464 A013465 * A013467 A013468 A013469

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified August 12 13:34 EDT 2022. Contains 356077 sequences. (Running on oeis4.)