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A009253 Expansion of exp(tan(x)/cos(x)). 0
1, 1, 1, 6, 21, 112, 717, 4592, 38857, 318208, 3158329, 32169984, 363525789, 4399544320, 56250039237, 779244812288, 11210469917713, 173483433263104, 2783865475754737, 47421793222656000, 840008000833503141 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..20.

MATHEMATICA

With[{nn=30}, CoefficientList[Series[Exp[Tan[x]/Cos[x]], {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Sep 30 2012 *)

CROSSREFS

Sequence in context: A060843 A026650 A298837 * A251593 A012840 A013320

Adjacent sequences:  A009250 A009251 A009252 * A009254 A009255 A009256

KEYWORD

nonn,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended and signs tested Mar 15 1997 by Olivier Gérard.

STATUS

approved

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Last modified February 19 15:01 EST 2018. Contains 299334 sequences. (Running on oeis4.)