Number of 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.

A078698

Number of 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) =20a(3) =396a(4) =14976a(5) =907200a(6) =79315200a(7) =9551001600

External references