Create A Sequence Of Values With A Step

The seq utility allows you to output a sequence of values.

You can start at 1 by default.

$ seq 3
1
2
3

Or you can specify the starting value.

$ seq 10 13
10
11
12
13

Adding a third argument in between those two will specify the step value that should be taken to get from one to the other.

$ seq 6 3 15
6
9
12
15

That sequence starts at 6 and goes to 15 with a step value of 3.

See man seq for more details.