A generative sequence is a linearly ordered series of patterns. Examples are given in The Timeless Way of Building, though that book does not yet name them 'generative sequences'. For a while I had called these 'pattern sentences' for lack of a better term. Generative sequence is better, or maybe just sequence, or pattern sequence... Well, in any case, the pivotal word is sequence.
~ Chapter 11 (THE SEQUENCE OF UNFOLDING) of The Nature of Order Book Two (THE PROCESS OF CREATING LIFE) (http://newforum.droqen.com/index.php?msg=1851) is where I first encountered this name, 'sequence' or 'generative sequence'.
~ In my design breakdown of Genshin Impact (https://newforum.droqen.com/index.php?msg=2693) I found myself writing such a generative sequence to practice understanding some part of its design in this way.