Good point and well spotted!

PS: Though it’s not actually called exponential (as it isn’t e^{nr-3-month-periods} but rather 2^{nr-3-month-periods} ) but has a different name which I can’t recall anymore.

PPS: Found it - it’s a “geometric progression”.

Neatly showing why when all you have is two data points you can’t just assume the best fit function for extrapolation is a linear one.

Mind you, a surprisingly large number of political comments is anchored in exactly that logic.