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A024303 Expansion of tan(tanh(x))*x/2. 0
0, 1, 0, -24, 448, -640, -658944, 56992768, -2831024128, -86998155264, 51519425740800, -9075812362878976, 917148920337924096, 26667007293767286784, -33058738844745936666624, 2573727989288825813729280, 4259701574179331481681264640 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..16.

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[Tan[Tanh[x]]*x/2, {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Aug 22 2017 *)

CROSSREFS

Cf. A009718.

Sequence in context: A004358 A006260 A187625 * A060195 A114201 A263476

Adjacent sequences:  A024300 A024301 A024302 * A024304 A024305 A024306

KEYWORD

sign

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs Mar 1997

More terms from and prior Mathematica program replaced by Harvey P. Dale, Aug 22 2017

STATUS

approved

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Last modified November 30 02:18 EST 2021. Contains 349416 sequences. (Running on oeis4.)