1/6 a^{}_{c0,c1,c2} b^{c0,c1,c2}_{}
+1/4 a^{}_{c0,c1,c4} b^{c2,c3,c4}_{} a+(c0) a+(c1) a-(c3) a-(c2)
+1/2 a^{}_{c0,c2,c3} b^{c1,c2,c3}_{} a+(c0) a-(c1)