Your task is to formulate an algorithm and make a CC that works with numbers. Let's take one parameter N, it has to be non-negative integer and given by user. Make a variable called $x and set it equal to N+3 Now count from 0 to N (both inclusive), and for each iteration (let's call it i) that you pass, return the value of x*(-i). After that update x to be equal to i*N+x. When counting finishes, return the value of variable $x.
If you do these steps for N=3, you should come up with the sequence of numbers 0 -6 -18 -45 24.
Generally, when we're programming, we don't like capital letters for variables. All capital letters is usually reserved for a constant, so we'll use lowercase $n for this variable henceforth.