Greens function of a free massive scalar field on the lattice
  We propose a method to calculate the Greens function of a free massive scalar field on the lattice numerically to very high precision. For masses m < 2 (in lattice units) the massive Greens function can be expressed recursively in terms of the massless Greens function and just two additional mass-independent constants. 
B. Borasoy, H. Krebs