How to make Recursive Calculus using multiple parameters

[Anonymous]

I am trying to make a recursive calculus that uses two parameters but it's not working. 

It gives the following error: 

An error occurred in the ‘’ query. Expression.Error: 1 arguments were passed to a function which expects 2.
Details:
Pattern=
Arguments=[List]

The strange thing is, when I remove the variation variable, it works. 

Does anyone knows how to tackle this problem?

[Greg_Deckler]

@Anonymous Yes, you need to pass in 2 parameters when you call the function because you specify that the function takes 2 parameters.