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A012169 sech(tan(arcsinh(x)))=1-1/2!*x^2+1/4!*x^4-1/6!*x^6+449/8!*x^8... 0
1, -1, 1, -1, 449, -31681, 3077185, -445157441, 87981830785, -22627780368001, 7353703042163585, -2948527179059299201, 1429774747400938052161, -824792570907860638058561, 558247886671770078618138049 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

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

CROSSREFS

Sequence in context: A283791 A036945 A201182 * A093402 A012062 A339978

Adjacent sequences:  A012166 A012167 A012168 * A012170 A012171 A012172

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified May 16 15:15 EDT 2022. Contains 353706 sequences. (Running on oeis4.)