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A009765 Expansion of tan(x/cos(x)). 5
1, 5, 101, 4689, 381769, 47849053, 8532452397, 2051184222377, 639121206054545, 250473754883360181, 120568689462321176053, 69926680208791530760705, 48091629862193464534126041 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..12.

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[Tan[x/Cos[x]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Jan 06 2012 *)

CROSSREFS

Sequence in context: A074790 A009757 A119556 * A113073 A275749 A057207

Adjacent sequences:  A009762 A009763 A009764 * A009766 A009767 A009768

KEYWORD

nonn

AUTHOR

R. H. Hardin

EXTENSIONS

Extended and signs tested Mar 15 1997 by Olivier Gérard.

STATUS

approved

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Last modified October 17 18:19 EDT 2018. Contains 316292 sequences. (Running on oeis4.)