Trial and error

Science is about trial and error: you make an error, then you go to trial.

Metamath problem

Find numbers N and M so you can construct a valid mathematical formula with:

• N factorial signs (!);
  
• M multiplication signs (*), numbers N, numbers M;
  
• one equal sign (=);
  
• in addition, a plus (+).
  

and as many parantheses as you want.