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Number of ways to lace a shoe that has n pairs of eyelets, assuming the lacing satisfies certain conditions.
1

%I #5 Mar 30 2012 16:49:37

%S 1,3,50,2122,155712,17441962

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

%C 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.

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

%H <a href="/index/La#lacings">Index entries for sequences related to shoe lacings</a>

%Y Apart from initial term, A078629/2.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Dec 16 2002