What is the minimum number of people needed to create a viable human breeding population?

I know that the plan from the Seventies was to build a habitat
for ten thousand, and have that population get busy building
another, and both of those populations build one more each,
until you had eight to sixteen habitats, each containing ten
thousand people.

Man, can I write a long sentence or what!

After that, the 80 thousand to 160 thousand people would
divide their efforts between building powersats and building
more habitats, with a percentage or two dedicated to
"everything else."

I'd imagine that eighty thousand to a hundred sixty thousand
should do it, especially if they're still building more
habitats and still taking on new immigrants.