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A278994 Number of simple chord diagrams with n chords, modulo all symmetries. 0
0, 1, 1, 4, 18, 116, 1060, 13019, 193425, 3313522, 63667788, 1351700744, 31390695708, 791372281393, 21523271532811, 628166776833181, 19582955637428422, 649472761243051940, 22833268501579122332, 848230375982060558217 (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: A137567 A326261 A277473 * A223008 A162224 A321704

Adjacent sequences:  A278991 A278992 A278993 * A278995 A278996 A278997

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 07 2016

STATUS

approved

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Last modified August 1 02:28 EDT 2021. Contains 346377 sequences. (Running on oeis4.)