Yes, but that's not what he says. He says "The loop will repeat on average n! times". That's not true. He's not referring to O notation there, he brings that in

Yes, but that's not what he says. He says "The loop will repeat on average n! times". That's not true. He's not referring to O notation there, he brings that in later. Here he's talking about the imperative number of times a loop will run on average. Edit: you've edited your paragraph to make my reply look silly. The whole paragraph is not in O notation. In fact - the exact opposite. In the last sentence of that paragraph he shows what the expression with constant factors looks like before converting it into O notation, and it's wrong! "The product (n-1)n! is O(n × n!)." Bzzzzzzt! Wrong! He should say "The product (n-1)(n!/2) is O(n × n!)."