The with_sequence parameter can be used to iterate over a sequence of numbers. In this example, the debug module is used iterate over a sequence of 0 through 10.

- name: sequence 0 to 3
  debug: 
    msg: "{{ item }}"
  with_sequence: start=0 end=3

Something like this should be returned.

TASK [sequence 0 to 3]
ok: [server1.example.com] => (item=0) => {
    "msg": "0"
}
ok: [server1.example.com] => (item=1) => {
    "msg": "1"
}
ok: [server1.example.com] => (item=2) => {
    "msg": "2"
}
ok: [server1.example.com] => (item=3) => {
    "msg": "3"
}

Or, perhaps a bit more practical example would be using the file module to create a sequence of files.

- name: create foo0.txt through foo3.txt
  file:
    path: /tmp/foo{{ item }}.txt
    state: touch
  with_sequence: start=0 end=3

The when parameter can be used as well.

- name: sequence 0 to 3
  set_fact: 
    foo: "{{ item }}"
  with_sequence: start=0 end=3
  when: foo|int < 2