I need to maximize a function that involves an alternate sum and a set of restrictions. I have tried the following code:

NMaximize ({(- 1) m * n!, N + m == 7, m> 0, n> 0}, {m, n})

However, the error message

```
NMaximize: The objective function {(-1)^m n!} should be scalar-valued
```

appears.

Is there a numerical maximization method that can be used for functions like this?