Number of ordered pairs (p,q) of permutations of [n] with equal up-down signatures and p(1)=q(1)=4.

A321060

Number of ordered pairs (p,q) of permutations of [n] with equal up-down signatures and p(1)=q(1)=4.

Terms

    a(0) =10a(1) =68a(2) =852a(3) =16328a(4) =438496a(5) =15608288a(6) =707767328a(7) =39729927744

External references