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A009819 tanh(tan(x)*tan(x))=2/2!*x^2+16/4!*x^4+32/6!*x^6-18944/8!*x^8... 2
0, 2, 16, 32, -18944, -2146048, -147605504, 12359002112, 9374161371136, 2762835317030912, 343159496128331776, -231213975915368808448, -236417180330506147856384, -118337919812286157284179968 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

MATHEMATICA

Tanh[ Tan[ x ]^2 ] (* Even Part *)

CROSSREFS

Sequence in context: A018975 A012696 A012392 * A189332 A230937 A018951

Adjacent sequences: A009816 A009817 A009818 * A009820 A009821 A009822

KEYWORD

sign

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved

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Last modified January 27 05:57 EST 2023. Contains 359837 sequences. (Running on oeis4.)