Number of 4n-length strings of balanced parentheses of exactly n different types that are introduced in ascending order.

A258399

Number of 4n-length strings of balanced parentheses of exactly n different types that are introduced in ascending order.

Terms

    a(0) =1a(1) =2a(2) =98a(3) =11880a(4) =2432430a(5) =714249900a(6) =275335499824

External references