Say I have a list 

```
Q = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18]

```

I believe I can extract the first and every ninth value thereafter using the extended slice notation:

```
Q[::9]

```

Which should give:

```
[0,9,18]

```

But how can I similarly select all the elements *apart from* those?