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A012455 sech(arctan(x)*tan(x))=1-12/4!*x^4-560/8!*x^8+241920/10!*x^10... 0
1, 0, -12, 0, -560, 241920, -8750016, 1727165440, -426305201920, 91939471712256, -31563179893517312, 13087008599986241536, -6237304648085400498176, 3651782585501269235793920 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

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

CROSSREFS

Sequence in context: A077351 A119530 A012332 * A120954 A265087 A012337

Adjacent sequences:  A012452 A012453 A012454 * A012456 A012457 A012458

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified May 28 07:30 EDT 2022. Contains 354112 sequences. (Running on oeis4.)