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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; internal format)
OFFSET

1,4

COMMENTS

Asymptotic estimate for A054499(n).

LINKS

A. Khruzin, Enumeration of chord diagrams

CROSSREFS

Sequence in context: A024076 A015553 A071878 * A192887 A000252 A078237

Adjacent sequences:  A104253 A104254 A104255 * A104257 A104258 A104259

KEYWORD

nonn

AUTHOR

Ralf Stephan, Mar 02 2005

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Last modified February 15 05:45 EST 2012. Contains 205694 sequences.