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A012670 arctan(tanh(x)*tan(x))=2/2!*x^2-128/6!*x^6+253952/10!*x^10... 1
2, -128, 253952, -2863136768, 107451055603712, -10140668012798148608, 2022780765718183801782272, -757569427466144902069404827648 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..7.

FORMULA

(-1)^n * 2^(6n+1) * A090681(n).

CROSSREFS

Sequence in context: A086190 A024345 A012524 * A209248 A153425 A296060

Adjacent sequences:  A012667 A012668 A012669 * A012671 A012672 A012673

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified October 14 12:17 EDT 2019. Contains 328005 sequences. (Running on oeis4.)