A090935 Number of rational knots with n crossings with unknotting gap.

1, 1, 5, 7, 31, 43, 138

Offset

10,3

References

S. A. Bleiler, A note on unknotting number, Math. Proc. Camb. Phil. Soc. 96 (1984) 469-471.

D. Garity, Unknotting numbers are not realized in minimal projections for a class of rational knots. Proceedings of the "II Italian-Spanish Congress on General Topology and its Applications" (Trieste, 1999). Rend. Istit. Mat. Univ. Trieste 32 (2001), suppl. 2, 59-72 (2002).

Y. Nakanishi, Unknotting numbers and knot diagrams with the minimum crossings, Math. Sem. Notes Kobe Univ. 11 (1983) 257-258.

Links

Table of n, a(n) for n=10..16.

D. Garity, Unknotting Numbers are not Realized in Minimal Projections for a Class of Rational Knots

S. Jablan and R. Sazdanovic, LinKnot

Example

The first knot with unknotting gap is 10_8=514 (Nakanishi-Bleiler example).
For n=11 there is a knot 4142, etc.

Crossrefs

Cf. A090936.

Sequence in context: A025119 A025095 A025114 * A359066 A153414 A284405

Adjacent sequences: A090932 A090933 A090934 * A090936 A090937 A090938

Keyword

nonn

Author

Slavik Jablan and Radmila Sazdanovic (jablans(AT)mi.sanu.ac.rs), Feb 26 2004; corrected Aug 29 2004

Status

approved