The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A013528 Numerator of [x^(2n)] of the Taylor series sech(cosec(x)-cot(x)) = 1 -x^2/8 -x^4/128 +x^6/15360 +19*x^8/294912 +25031*x^10/3715891200+... . 1
1, -1, -1, 1, 19, 25031, 18421, -622177, -283401163, -24826632949, -2243454779, 4882905709651, 43798187793808543, -46704901267812186793, -5325187532598955153807 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,5
COMMENTS
The e.g.f. related to x/2, sech(cosec(x)-cot(x)) = 1 -1*x^2/(2^2*2!) -3*x^4*(2^4*4!) +3*x^6/(2^6*6!) +665*x^8/(2^8*8!) +.. is (up to signs) apparently provided by A009011.
LINKS
MATHEMATICA
Numerator[Take[CoefficientList[Series[Sech[Csc[x] - Cot[x]], {x, 0, 50}], x], {1, -1, 2}]] (* G. C. Greubel, Nov 12 2016 *)
CROSSREFS
Sequence in context: A125043 A249907 A233105 * A172762 A203703 A068734
KEYWORD
sign,frac
AUTHOR
Patrick Demichel (patrick.demichel(AT)hp.com)
EXTENSIONS
Name edited by R. J. Mathar, Dec 20 2011
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 23 05:11 EDT 2024. Contains 372758 sequences. (Running on oeis4.)