GEOMETRIC SERIES PRESENT WORTH FACTOR
Factor that yields the present value of a set of annual payments that are escalating geometrically. This factor, called the geometric series present worth factor and designated as T GP,i,e,n calculates the present value in terms of the first year payment G and the escalation rate e, as well as the discount rate i and period n. The relationship is P = G T GP,i,e,n where
T GP,i,e,n = [(1 + i) n -(1 + e) n]/[( i - e)(1+i ) n]