Group by a range of values

Say I have a field of ints, as for example created by with ordinality or generate_series, is it possible to group by a range? eq

1,2,3,4,5,6,7,8,9,10

step 3

so output is

1 1

2 1

3 1

4 2

5 2

6 2

7 3

8 3

9 3

10 4

thanks