For the 17-water cluster, with the complex always being included as one of the monomers in the calculations, we can evaluate 17!/(2!(17 -2)!) = 136 V 3B -terms. Lastly, by using the recursive relation in equation 8 we can obtain the sum of all n-body interactions of the 18-body (17 waters + 1 complex) system with n ≥ 3 as: