Offhand, I think you would also need to know the number of generations. I'll have to do some pen-and-paper work to work out what the distribution looks like.
Huh? Why? The expected number of blobs is given by N/(1-p), the number of actually realized generations is not a variable, it's determined by N, p and chance. I have no idea how the distribution looks, but the number of actual generations should be one of the things you have a distribution across, not an input.
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