-1/2 a^{a0,a3}_{c0} b^{}_{a1,a2,a4} eta1^{a4}_{a3} a+(c0) a+(a1) a+(a2) a-(a0)
+1/2 a^{a1,a2}_{c0} b^{}_{a0,a3,a4} eta1^{a4}_{a2} eta1^{a3}_{a1} a+(c0) a+(a0)
+1/4 a^{a1,a2}_{c0} b^{}_{a0,a3,a4} lambda2^{a3,a4}_{a1,a2} a+(c0) a+(a0)