A human proof for a generalization of Shalosh B. Ekhad's 10^n Lattice Paths Theorem

Nicholas A. Loehr, Bruce E. Sagan, Gregory S. Warrington

Consider lattice paths in Z^2 taking unit steps north (N) and east (E). Fix positive integers r,s and put an equivalence relation on points of Z^2 by letting v,w be equivalent if v…