How to generate a number sequence in file using vi or Vim?

Question

Is there a way to generate a number sequence in vi or Vim?

For example, for an arbitrary range of lines i  through j (where i < j

Answer 1

Select several lines with V(Shift-v), then type command bellow:

:let i=1 | '<,'>g/^/ s//\=i . " "/ | let i+=2

_{Type :help sub-replace-expression to read more.}