The Advanced Random plugin is really useful for a variety of things, notably procedural generation via its noise-generation functions. But it also allows you to...
These sorts of questions are best asked in the forums really, but as a basic example, you could create the permutation table on the start of the layout, then when a key is pressed you'd iterate through a 'For' loop the same size as the permutation table to spawn that many sprites and assign them an animation frame that matches the loopindex.