1/2 a^{a1}_{c0,a0} b^{c3}_{c1,c2,a2} eta1^{a2}_{a1} a+(c0) a+(c1) a+(c2) a+(a0) a-(c3)
+1/2 a^{a1}_{c2,a0} b^{c2}_{c0,c1,a2} a+(c0) a+(c1) a+(a0) a+(a2) a-(a1)
-1/2 a^{a1}_{c2,a0} b^{c2}_{c0,c1,a2} eta1^{a2}_{a1} a+(c0) a+(c1) a+(a0)