Come up with a formula for n years that has previous years result as input for next year Look at the following sequence:
$\text{year }1 = 2x-0.5x = 1.5x
$
$\text{year }2 = 2(1.5x) - 0.5(1.5x) = 2.25x$
$\text{year }3 = 2(2.25x) - 0.5(2.25x)$
How do I come up with a generic formula to continue this calculation for $n$ years?

According to the message I got from the question, ${y_n}$ is a geometric sequence, which acts like:
$$y_n=2y_{n-1}-0.5y_{n-1}=1.5y_{n-1}.$$
$$\dfrac{y_n}{y_{n-1}}=1.5$$
$$y_n = 1.5y_{n-1} = (1.5)^2y_{n-2}=\dots=(1.5)^{n}y_0 = (1.5)^n x.$$
I don't know if I misunderstood what you mean. If so, I'll be super sorry about that!
