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A012840 exp(sec(x)*arctanh(x))=1+x+1/2!*x^2+6/3!*x^3+21/4!*x^4+120/5!*x^5... 1
1, 1, 1, 6, 21, 120, 765, 5376, 46473, 415104, 4371225, 48143744, 594635613, 7784817664, 110691178325, 1673986906112, 27018807872657, 462531126525952, 8370279766396593, 159859054841331712 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..19.

CROSSREFS

Sequence in context: A298837 A009253 A251593 * A013320 A056308 A081077

Adjacent sequences:  A012837 A012838 A012839 * A012841 A012842 A012843

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified October 28 17:59 EDT 2021. Contains 348329 sequences. (Running on oeis4.)