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A278993 Number of simple chord diagrams with n chords, up to rotation. 0
0, 1, 1, 4, 21, 176, 1893, 25030, 382272, 6604535, 127222636, 2702798537, 62778105236, 1582725739329, 43046433007765, 1256332883208474, 39165907107963273, 1298945495674093932, 45666536827274985585, 1696460750775267473762 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..20.

E. Krasko, A. Omelchenko, Enumeration of Chord Diagrams without Loops and Parallel Chords, arXiv preprint arXiv:1601.05073 [math.CO], 2016.

E. Krasko, A. Omelchenko, Enumeration of Chord Diagrams without Loops and Parallel Chords, The Electronic Journal of Combinatorics, 24(3) (2017), #P3.43.

CROSSREFS

Sequence in context: A078670 A317104 A163948 * A306067 A230682 A231220

Adjacent sequences:  A278990 A278991 A278992 * A278994 A278995 A278996

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 07 2016

STATUS

approved

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Last modified July 23 12:19 EDT 2021. Contains 346259 sequences. (Running on oeis4.)