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A012018 sech(sin(tan(x)))=1-1/2!*x^2+1/4!*x^4+47/6!*x^6+897/8!*x^8... 0
1, -1, 1, 47, 897, 26911, 2176769, 269558351, 38463601409, 6445724731199, 1297792574780417, 307585734223517551, 82426762826906376833, 23816926512873022989919, 6844111898535212011277057 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..14.

CROSSREFS

Sequence in context: A262120 A032626 A009054 * A010963 A234354 A161692

Adjacent sequences:  A012015 A012016 A012017 * A012019 A012020 A012021

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified April 5 00:43 EDT 2020. Contains 333238 sequences. (Running on oeis4.)