%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