The thing you're looking for here isn't a sequencer...it's a clock multiplier, and the function you're talking about is "ratcheting". Have a look at Doepfer's A-160-5. That module can output multiple clock pulses based on an incoming clock, and the amount of repetitions can be voltage-controlled. Now, as to how to get it to work...that's going to vary from sequencer to sequencer that you use it with. By and large, though, you're looking at clock modulation and logic functions when you're talking about something of this sort. In some cases, you might be able to trigger the ratcheting from a stage pulse. Others might require something a bit more elaborate with some logic gating. It all more or less depends on which sequencer seems like a good fit for you...and once you sort that out, then the next step will be figuring out how clocking should work for you and all of the related fun with that.