∑j13⁢j24(-1)2⁢j2+j24+j23-j34⁢(2⁢j13+1)⁢(2⁢j24+1)⁢{j1j2j12j3j4j34j13j24j}⁢{j1j3j13j4j2j24j14j23j}={j1j2j12j4j3j34j14j23j}.