Number of ordered pairs (p,q) of permutations of [2n] with equal up-down signatures and p(1)=q(1)=n.
A262379
Number of ordered pairs (p,q) of permutations of [2n] with equal up-down signatures and p(1)=q(1)=n.
Terms
- a(0) =1a(1) =1a(2) =8a(3) =852a(4) =438496a(5) =678914816
External references
- oeis: A262379