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

 

Logo

"Email this user" was broken Aug 14 to 9am Aug 16. If you sent someone a message in this period, please send it again.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A013324 Numerator of [x^n] of the Taylor series arccosh(exp(x)-tanh(x))= x+x^2/2 -x^3/8 -7*x^4/48 +3*x^5/128 +631*x^6/11520 +37*x^7/15360 -12731*x^8/645120 -... 0
1, 1, -1, -7, 3, 631, 37, -12731, -37481, 771163, 590381, -195597517, -8025539, -205204695149, 5456117628779, 3973785585851, -3056850228539, -168086791499223239 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

The e.g.f. at x/2 seems to admit an integer representation: arccosh(exp(x)-tanh(x)) = 2*x/(2*1!) +4*x^2/(2^2*2!) -6*x^3/(2^3*3!) -56*x^4/(2^4*4!) +90*x^5/(2^5*5!) +2524*x^6/(2^6*6!) ...

LINKS

Table of n, a(n) for n=1..18.

CROSSREFS

Sequence in context: A054471 A086453 A112099 * A110792 A221388 A175998

Adjacent sequences:  A013321 A013322 A013323 * A013325 A013326 A013327

KEYWORD

sign,frac

AUTHOR

Patrick Demichel (patrick.demichel(AT)hp.com)

EXTENSIONS

Values replaced by numerators. - R. J. Mathar, Dec 22 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 | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified August 18 23:34 EDT 2017. Contains 290780 sequences.