The product of the first n terms of an arithmetic progression may be developed in a polynomial of n terms. Each one of them presents a coefficient C nk that is independent from the initial term and the common difference of the progression.The most interesting point is that one may construct an "Arithmetic Triangle", displaying these coefficients, in a similar way one does with Pascal's Triangle. Moreover, some remarkable properties, mainly concerning factorials, characterize the Triangle. Other related 'triangles' -eventually treated as matrices -also display curious facts, in their linear modus operandi, such as successive "descendances".