There's a big red disclaimer at the top of the page: "Ancient CS 61 Content Warning!!!!!1!!! This is not the current version of the class. This site was automatically translated from a wiki. The translation may have introduced mistakes (and the content might have been wrong to begin with)."

The description of `seq` isn't even correct: "If a second argument is provided, the numbers will stop printing at the once the second number has been reached. Otherwise, the numbers will continue forever"

Nope, `seq`'s arguments are defined as `[first [incr]] last`. With a single argument, it counts up from 1 to `last`. Maybe some previous version of `seq` behaved differently, but not as far as I can recall.

But again, can't hold anything against the page given the disclaimer.