I'm trying a regex fro Alpha Numeric of length 7 (with positions 1,3,4 as characters and positions 2,5,6,7 as digits).

```
[a-zA-Z]|[0-9]|[a-zA-Z]|[a-zA-Z]|[0-9]|[0-9]|[0-9]

```

Can someone help me?