A078674 Number of ways to lace a shoe that has n pairs of eyelets, assuming the lacing satisfies certain conditions.

1, 3, 50, 2122, 155712, 17441962

Offset

1,2

Comments

The lace must follow a Hamiltonian path through the 2n eyelets and cannot pass in order though three adjacent eyelets that are in a line.

The lace is "undirected": reversing the order of eyelets along the path does not count as a different solution (cf. A078629).

Links

Table of n, a(n) for n=1..6.

Index entries for sequences related to shoe lacings

Crossrefs

Apart from initial term, A078629/2.

Sequence in context: A279970 A217767 A185157 * A071094 A144987 A304055

Adjacent sequences: A078671 A078672 A078673 * A078675 A078676 A078677

Keyword

nonn

Author

N. J. A. Sloane, Dec 16 2002

Status

approved