Number of endofunctions f on [2n] satisfying f^n(i) = i for all i in [n].

A246071

Number of endofunctions f on [2n] satisfying f^n(i) = i for all i in [n].

Terms

    a(0) =1a(1) =2a(2) =50a(3) =1440a(4) =215760a(5) =11218000a(6) =8859219696a(7) =549669946784

External references