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A264761 Number of irreducible indecomposable spherical curves with n crossings (only ordinary double points), the circle is oriented, the sphere is oriented (OO case). 3
0, 0, 1, 1, 2, 6, 17, 73, 290, 1274, 5844, 27750, 135192, 676263 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Irreducible means not made disconnected by removal of a vertex (no nugatory crossings).

Indecomposable (or prime) means not made disconnected by cutting two distinct lines.

LINKS

Table of n, a(n) for n=1..14.

J. Betrema, Tait Curves

R. Coquereaux, J.-B. Zuber, Maps, immersions and permutations, arXiv preprint arXiv:1507.03163, 2015. Also J. Knot Theory Ramifications 25, 1650047 (2016), DOI: http://dx.doi.org/10.1142/S0218216516500474

PROG

(C) See the J. Betrema C program in the Tait Curves link.

CROSSREFS

Cf. A008986, A008987, A008988, A008989, A007756, A264759, A264760.

Sequence in context: A150039 A150040 A079456 * A253882 A327698 A183757

Adjacent sequences:  A264758 A264759 A264760 * A264762 A264763 A264764

KEYWORD

nonn,more

AUTHOR

Robert Coquereaux, Nov 23 2015

STATUS

approved

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Last modified October 25 01:18 EDT 2020. Contains 338010 sequences. (Running on oeis4.)