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A012463 tanh(arctan(x)*arctan(x))=2/2!*x^2-16/4!*x^4+128/6!*x^6+9984/8!*x^8... 0
0, 2, -16, 128, 9984, -1686528, 211630080, -21438504960, -115777536000, 1290343156285440, -677718502185369600, 262776565415742013440, -69499554745499013611520, -9137401716948937432104960 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[Tanh[ArcTan[x]*ArcTan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Ray Chandler, Nov 28 2016 *)

CROSSREFS

Sequence in context: A161737 A171451 A012459 * A037517 A037720 A022018

Adjacent sequences:  A012460 A012461 A012462 * A012464 A012465 A012466

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified August 20 22:45 EDT 2019. Contains 326155 sequences. (Running on oeis4.)