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A009367

Expansion of e.g.f.: log(1+tan(tanh(x))).

0, 1, -1, 2, -6, 16, -72, 496, -3248, 24064, -208384, 1908224, -19624704, 227958784, -2800573440, 36620830720, -519452284928, 7865201852416, -126035093291008, 2142236553248768, -38449509963399168, 725477781101608960

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OFFSET

0,4

LINKS

Table of n, a(n) for n=0..21.

FORMULA

a(n) ~ (n-1)! * (-1)^(n+1) * 2^n / (log((4+Pi)/(4-Pi)))^n. - Vaclav Kotesovec, Jan 23 2015

MATHEMATICA

With[{nn=30}, CoefficientList[Series[Log[1+Tan[Tanh[x]]], {x, 0, nn}], x]Range[0, nn]!] (* Harvey P. Dale, Sep 14 2012 *)

CROSSREFS

Sequence in context: A009186 A009328 A009346 * A114249 A147910 A147902

Adjacent sequences: A009364 A009365 A009366 * A009368 A009369 A009370

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

Definition clarified by Harvey P. Dale, Sep 14 2012

STATUS

approved

URL: https://oeis.org/A009367

⇱ A009367 - OEIS