cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Previous Showing 11-13 of 13 results.

A383829 Number of medial involutory racks of order n, up to isomorphism.

Original entry on oeis.org

1, 1, 2, 5, 12, 38, 168, 850, 6090
Offset: 0

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Author

Luc Ta, May 11 2025

Keywords

Comments

A rack is involutory if it satisfies the identity y(yx) = x. In particular, involutory quandles are called kei.
A rack is medial if it satisfies the identity (xy)(uv) = (xu)(yv).
a(n) is also the number of medial Legendrian kei (i.e., medial kei equipped with Legendrian structures) up to order n up to isomorphism; see Ta, Theorem 1.1.
a(n) is also the number of medial symmetric kei (i.e., medial kei equipped with good involutions) up to order n up to isomorphism; see Ta, "Equivalences of...," Corollary 1.3.

References

  • Seiichi Kamada, Quandles with good involutions, their homologies and knot invariants, Intelligence of Low Dimensional Topology 2006, World Scientific Publishing Co. Pte. Ltd., 2007, pages 101-108.

Crossrefs

Programs

  • GAP
    # See Ta, GitHub link

A383830 Number of Legendrian quandles of order n, up to isomorphism.

Original entry on oeis.org

1, 1, 2, 5, 15, 54, 240, 1306, 9477
Offset: 0

Views

Author

Luc Ta, May 11 2025

Keywords

Comments

A Legendrian quandle is a pair (X,u) where X is a quandle and u is an involutory automorphism of X such that u(yx)=y(u(x)); see Ta, "Generalized Legendrian...," Corollary 3.13.
a(n) is also the number of racks X such that the kink map X -> X defined by x -> x(x) is an involution; see Ta, "Equivalences of...," Theorem 1.1.

Crossrefs

Programs

  • GAP
    # See Ta, GitHub link

A376155 Number of prime knots with 10 or fewer crossings whose mosaic number is n.

Original entry on oeis.org

0, 1, 0, 1, 6, 96, 146
Offset: 1

Views

Author

Luc Ta, Sep 12 2024

Keywords

Comments

An n X n mosaic is an n X n array of the 11 tiles given by Lomonaco and Kauffman. The mosaic number of a knot K is the smallest integer n such that K is realizable on an n X n knot mosaic.
Here, we count the unknot as a prime knot.

Examples

			There are exactly 6 prime knots that are realizable on a 5 X 5 knot mosaic but not realizable on a 4 X 4 knot mosaic. Namely, these knots are 4_1, 5_1, 5_2, 6_1, 6_2, and 7_4 (see Table 1 of Lee et al.). Hence, a(5) = 6.
		

Crossrefs

Previous Showing 11-13 of 13 results.