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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A104256 [ (2n-1)!!/(4n) ]. 1
0, 0, 1, 6, 47, 433, 4826, 63344, 957206, 16368226, 312484331, 6588211317, 152035645781, 3811750833515, 103171389227156, 2998418499414228, 93127351040630156, 3078376326065274609, 107905191218919625781 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Asymptotic estimate for A054499(n).

LINKS

Table of n, a(n) for n=1..19.

A. Khruzin, Enumeration of chord diagrams

CROSSREFS

Sequence in context: A015553 A291028 A071878 * A289211 A192887 A320403

Adjacent sequences:  A104253 A104254 A104255 * A104257 A104258 A104259

KEYWORD

nonn

AUTHOR

Ralf Stephan, Mar 02 2005

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 20 13:57 EDT 2018. Contains 316379 sequences. (Running on oeis4.)