a(n) = (6*n)!/((3*n)!*(2*n)!*n!).A113424a(n) = (6*n)!/((3*n)!*(2*n)!*n!).Terms a(0) =1a(1) =60a(2) =13860a(3) =4084080a(4) =1338557220a(5) =465817912560External referencesoeis: A113424