login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A009708 Expansion of tan(tan(x)/cos(x)). 0
1, 7, 177, 10519, 1108833, 180134183, 41643888145, 12982974409271, 5247381641852609, 2667871676330509895, 1666128949779524612977, 1253728661849677130856279, 1118729647152655182634160673 (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[Tan[x]/Cos[x]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Oct 13 2014 *)

CROSSREFS

Sequence in context: A152930 A027489 A098433 * A231490 A231489 A221110

Adjacent sequences:  A009705 A009706 A009707 * A009709 A009710 A009711

KEYWORD

nonn

AUTHOR

R. H. Hardin

EXTENSIONS

Extended and signs tested Mar 15 1997 by Olivier Gérard.

Prior Mathematica program replaced by Harvey P. Dale, Oct 13 2014

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 6 18:42 EDT 2020. Contains 333286 sequences. (Running on oeis4.)