1/2 a^{}_{c0,a0} b^{c1,c2,a1}_{} gamma1^{a0}_{a1} a+(c0) a-(c2) a-(c1)
+a^{}_{c1,a0} b^{c0,c1,a1}_{} a+(a0) a-(a1) a-(c0)
+a^{}_{c1,a0} b^{c0,c1,a1}_{} gamma1^{a0}_{a1} a-(c0)