Repeating a sequence of numbers down a column

[Guest]

Is there any way to fill down a column with a repeating sequence of numbers?
In other words, instead of 1, 2, 3, 4, 5, 6..., I want the column to fill
down with 1, 2, 3, 1, 2, 3, 1, 2, 3...

 

[Peo Sjoblom]

Put 1 , 2 3 in the first 3 cells, select them. right click and drag copy
down,
upon releasing the right mouse button you'll get an option of copy cells,
select it

 

[Guest]

Enter 1 at the top (A1 or whatever)
In A2, enter =MOD(A1,3)+1
Copy A2