Number of symmetric ways to lace a shoe that has n pairs of eyelets such that each eyelet has at least one direct connection to the opposite side.

A078700

Number of symmetric ways to lace a shoe that has n pairs of eyelets such that each eyelet has at least one direct connection to the opposite side.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =30a(4) =192a(5) =1560a(6) =15120a(7) =171360a(8) =2217600a(9) =32296320a(10) =522547200a(11) =9300614400a(12) =180583603200

External references