  Using the generating function of SU(n) we find the conjugate state of SU(n)
basis and we find in terms of Gel'fand basis of SU(3(n-1)) the representation
of the invariants of the Kronecker products of SU(n). We find a formula for the
number of the elementary invariants of SU(n). We apply our method to the
coupling of SU(3) and we find a new expression of the isoscalar of Wigner
symbols ($\lambda 10,\lambda 2 \mu 2; \lambda 3 \mu 3$).
