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A Mars Colony Needs Just 22 People to Survive, Simulation Suggests
(www.extremetech.com)
This is a most excellent place for technology news and articles.
I don't know where i got this same number, maybe in a course talking about genealogy in school, a'd i use it since then.
Iirc, the Matrix used that same number for determining how many humans to leave alive outside of the matrix so that the community wound be self-sustaining before they were able to ramp up breaking people out again.