Is it a mistake in TAOCP
Maggie McLoughlin <mam@theory.stanford.edu> to Windreamer
Sequences with n=0 are empty. It's important in mathematics
to deal with empty sets and strings etc in a meaningful way.
If n = 0 and you're supposed to do something for 1 <= j <= n,
you don't have to do anything.
Thanks for your interest in my book! -- Don Knuth
呵呵，原來是我年少無知了，再次贊一下Knuth爺爺寫書的精致