Number of ordered pairs (p,q) of permutations of [n] with equal up-down signatures and p(1)=q(1)=3.

A321059

Number of ordered pairs (p,q) of permutations of [n] with equal up-down signatures and p(1)=q(1)=3.

Terms

    a(0) =2a(1) =8a(2) =64a(3) =852a(4) =17008a(5) =467696a(6) =16860608a(7) =769534688a(8) =43316046592

External references