In here, I present a series of combinatorial equalities derived using a graph based approach. Different nodes in the graphs are visited following probabilistic dynamics of a moving dot. The results are presented in such a way that the generalisation (to more nodes, or dimensions) is straightforward. At an instant m, we "take a picture" of the system and we compute the probabilities of being at particular positions in space. The sum of all these probabilities is equal to one.