a(n) = 4^n*(3*n)!/((2*n)!*n!).

A006588

a(n) = 4^n*(3*n)!/((2*n)!*n!).

Terms

    a(0) =1a(1) =12a(2) =240a(3) =5376a(4) =126720a(5) =3075072a(6) =76038144a(7) =1905131520a(8) =48199827456

External references