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A009818 Expansion of e.g.f.: tanh(tan(x)/cos(x)). 0
1, 3, -23, -2149, -73967, 4773747, 1496400505, 166245767819, -17997337551071, -15656779903415325, -4002361029690394103, 437839261718446458491, 1025307746504958768359473, 499247007876089430591206739 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
MATHEMATICA
With[{nn=30}, Take[CoefficientList[Series[Tanh[Tan[x]/Cos[x]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, May 21 2021 *)
CROSSREFS
Sequence in context: A088056 A009593 A351107 * A210734 A166315 A371346
KEYWORD
sign
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
Definition clarified and prior Mathematica program replaced by Harvey P. Dale, May 21 2021
STATUS
approved

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Last modified July 21 11:45 EDT 2024. Contains 374472 sequences. (Running on oeis4.)