Abstract factorials of arbitrary sets of integers
Angelo B. Mingarelli · arXiv (Cornell University) · 2007
Given any subset of Z we associate to it another set on which we can define one or more (generally independent) abstract factorial functions. These associated sets are studied and arithmetic relations are revealed. In addition, we show that for an abstract factorial function of an infinite subset of Z the series of reciprocals of its factorials is always an irrational number.