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A012154 sech(tan(tan(x)))=1-1/2!*x^2-11/4!*x^4-253/6!*x^6-9015/8!*x^8... 0
1, -1, -11, -253, -9015, -362009, 2294909, 7143505067, 2709263596817, 958529947538255, 359564035447469189, 146418020203030157779, 64393370639942123229401, 29924760789755403918019639 (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: A190680 A089298 A274129 * A009055 A009067 A128683

Adjacent sequences:  A012151 A012152 A012153 * A012155 A012156 A012157

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified September 17 19:02 EDT 2019. Contains 327137 sequences. (Running on oeis4.)