Schroeder's second problem (generalized parentheses); also called super-Catalan numbers or little Schroeder numbers.

A001003

Schroeder's second problem (generalized parentheses); also called super-Catalan numbers or little Schroeder numbers.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =11a(4) =45a(5) =197a(6) =903a(7) =4279a(8) =20793a(9) =103049a(10) =518859a(11) =2646723a(12) =13648869a(13) =71039373a(14) =372693519a(15) =1968801519a(16) =10463578353a(17) =55909013009a(18) =300159426963

External references