Geometric series: starts from <seed> and returns a list with f(i) = factor * f(i-1) <limit> is the limit of returned list list. <begin> and <end> allow to delimit the series. <nummax> allows to limit the number of elements. Ex. (geometric-ser 1 3 60) => (1 3 9 27) Ex. (geometric-ser 2 3 60) => (2 6 18 54)