How can I find an x (formula) that satisfies all the equations below for every integer n > 1?

```
n = 2 => 2 + x = 3
n = 3 => 3 + x = 3
n = 4 => 4 + x = 6
n = 5 => 5 + x = 6
n = 6 => 6 + x = 9
n = 7 => 7 + x = 9
n = 8 => 8 + x = 12
n = 9 => 9 + x = 12
n = 10 => 10 + x = 15
n = 11 => 11 + x = 15
…

```

Sorry if this sounds primitive, I can't seem to get it.