For derivatives, we use $f'(x), f''(x),$ etc. until that comes too unwieldy so we just use $f^{(n)} (x)$
What about for anti derivatives? I've seen using $F(x)$ to denote the first antiderivative of $f(x)$, but what would one do if you want to find the second anti derivative of $f(x)$? What would that be denoted by?
I've never come across this before, but a conventional notation could be:
For the first antiderivative $F_1(x)$ and for the second $F_2(x)$