678914816
domain: N
Appears in sequences
- Number of ordered pairs (p,q) of permutations of [2n] with equal up-down signatures and p(1)=q(1)=n.at n=5A262379
- Number of ordered pairs (p,q) of permutations of [n] with equal up-down signatures and p(1)=q(1)=5.at n=5A321061
- Number of ordered pairs (p,q) of permutations of [n] with equal up-down signatures and p(1)=q(1)=6.at n=4A321062