a(n) = (6*n)!*(2*n/3)!/((3*n)!*(2*n)!*(5*n/3)!).

A364175

a(n) = (6*n)!*(2*n/3)!/((3*n)!*(2*n)!*(5*n/3)!).

Terms

    a(0) =1a(1) =36a(2) =3564a(3) =408408a(4) =49697388a(5) =6249195036a(6) =802241960520

External references