-1/48 a^{a0,a3}_{} b^{}_{c0,c1,c2,c3} c^{}_{a1,a2,a4} eta1^{a4}_{a3} a+(c0) a+(c1) a+(c2) a+(c3) a+(a1) a+(a2) a-(a0)
+1/48 a^{a1,a2}_{} b^{}_{c0,c1,c2,c3} c^{}_{a0,a3,a4} eta1^{a4}_{a2} eta1^{a3}_{a1} a+(c0) a+(c1) a+(c2) a+(c3) a+(a0)
+1/96 a^{a1,a2}_{} b^{}_{c0,c1,c2,c3} c^{}_{a0,a3,a4} lambda2^{a3,a4}_{a1,a2} a+(c0) a+(c1) a+(c2) a+(c3) a+(a0)