Every other number is divisible by two.

1 2 3 4 5 6 7 8 9
F T F T F T F T F
F F T F F T F F T
And every third number is divisible by three.

So why can't people make a function based on this pattern to predict the prime numbers?

You know what the sequence is and you know whenever you have to add a new sequence is every new prime number.

How come anybody can't just make a function that accounts for new sequences and adapts like this and extends the pattern to infinity?