a^{a3,v0}_{c1,a0} b^{v1}_{a1} c^{c0,c1}_{a2,a4} eta1^{a4}_{a3} a+(a0) a+(a1) a+(a2) a-(v1) a-(v0) a-(c0)
+1/2 a^{a3,v0}_{c1,a0} b^{v1}_{a4} c^{c0,c1}_{a1,a2} eta1^{a4}_{a3} a+(a0) a+(a1) a+(a2) a-(v1) a-(v0) a-(c0)