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A013008 sech(arctan(x)+tan(x))=1-4/2!*x^2+80/4!*x^4-4384/6!*x^6+451328/8!*x^8... 0
1, -4, 80, -4384, 451328, -74726784, 18162914304, -6087614197760, 2690808196562944, -1516485688823611392, 1061352718471077658624, -903110171035290053246976, 918161695966849718656434176 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..12.

CROSSREFS

Sequence in context: A012042 A013139 A013007 * A013180 A322751 A000316

Adjacent sequences: A013005 A013006 A013007 * A013009 A013010 A013011

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified March 28 21:03 EDT 2023. Contains 361596 sequences. (Running on oeis4.)