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A264759 Number of irreducible indecomposable spherical curves with n crossings (only ordinary double points), the circle is not oriented, the sphere is not oriented (UU case). 3
0, 0, 1, 1, 2, 3, 10, 27, 101, 364, 1610, 7202, 34659, 170692 (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, A264760, A264761.

Sequence in context: A134588 A000060 A089752 * A323680 A171190 A216332

Adjacent sequences:  A264756 A264757 A264758 * A264760 A264761 A264762

KEYWORD

nonn,more

AUTHOR

Robert Coquereaux, Nov 23 2015

STATUS

approved

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Last modified March 18 19:58 EDT 2019. Contains 321293 sequences. (Running on oeis4.)