Number of 2n-length strings of balanced parentheses of exactly 2 different types that are introduced in ascending order.
A258390
Number of 2n-length strings of balanced parentheses of exactly 2 different types that are introduced in ascending order.
Terms
- a(0) =2a(1) =15a(2) =98a(3) =630a(4) =4092a(5) =27027a(6) =181610a(7) =1239810a(8) =8582756a(9) =60138078a(10) =425800564a(11) =3042175500a(12) =21906338040a(13) =158830645635
External references
- oeis: A258390