login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A101922 Numerators of expansion of e.g.f. 2^(-1/2) * arcsinh(cos(x)), even powers only. 3
-1, -1, 11, 491, 11159, -460681, -103577629, -8160790429, 624333860399, 386787409545839, 68810049201689531, -6999828208693648549, -9872674440874152431161, -3255253386897615662908441 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

With sign pattern +--+--: numerators of expansion of 2^(-1/2) * arcsinh(cosh(x)).

Odd coefficients are zero, denominators are 2^n.

LINKS

Table of n, a(n) for n=1..14.

FORMULA

arcsinh(cos(x)) = log(sqrt(2)+1) + 1/sqrt(2) * (-(1/2)*x^2/2! - (1/4)*x^4/4! + (11/8)*x^6/6! + (491/16)*x^8/8! + ...).

arccosh(cos(x)) = Pi/2 - log(sqrt(2)+1) + 1/sqrt(2) * ((1/2)*x^2/2! + (1/4)*x^4/4! - (11/8)*x^6/6! - (491/16)*x^8/8! - ...).

CROSSREFS

Cf. A101924, A012495.

Sequence in context: A156863 A145516 A041931 * A263246 A263377 A142809

Adjacent sequences:  A101919 A101920 A101921 * A101923 A101924 A101925

KEYWORD

sign

AUTHOR

Ralf Stephan, Dec 27 2004

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 17 07:57 EDT 2018. Contains 316276 sequences. (Running on oeis4.)