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A004300 Number of symmetric irreducible diagrams with 2n nodes.
(Formerly M1758)
3
1, 1, 2, 7, 22, 96, 380, 1853, 8510, 44940, 229836, 1296410, 7211116, 43096912, 256874200, 1617413773, 10226972110, 67542201972, 449809389740, 3104409032126 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

M. Klazar, Non-P-recursiveness of numbers of matchings or linear chord diagrams with many crossings, Advances in Appl. Math., Vol. 30 (2003), pp. 126-136.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

R. R. Stein, On a class of linked diagrams, I. Enumeration, J. Combin. Theory, A 24 (1978), 357-366.

R. R. Stein and C. J. Everett, On a class of linked diagrams, II. Asymptotics, Discrete Math., 21 (1978), 309-318.

LINKS

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

Jonathan Burns, Assembly Graph Words - Single Transverse Component (Counts).

Jonathan Burns, Egor Dolzhenko, Natasa Jonoska, Tilahun Muche, and Masahico Saito, Four-Regular Graphs with Rigid Vertices Associated to DNA Recombination, May 23, 2011.

Jonathan Burns and Tilahun Muche, Counting Irreducible Double Occurrence Words, arXiv preprint arXiv:1105.2926, 2011.

CROSSREFS

Cf. A000699.

Sequence in context: A150333 A057787 A217138 * A049369 A308548 A153523

Adjacent sequences:  A004297 A004298 A004299 * A004301 A004302 A004303

KEYWORD

nonn,nice,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified August 21 05:48 EDT 2019. Contains 326162 sequences. (Running on oeis4.)