One of the easiest ways to generate a list of numbers in Linux is to use the seq (sequence) command. In its simplest form, seq will take a single number and then list all the numbers from 1 to that number. For example:
$ seq 5 1 2 3 4 5
Unless directed otherwise, seq always starts with 1. You can start a sequence with a different number by inserting it before the final number.
$ seq 3 5 3 4 5
Specifying an increment
You can also specify an increment. Say you want to list multiples of 3. Specify your starting point (first 3 in this example), increment (second 3) and end point (18).
Thanks to Sandra Henry-Stocker (see source)