But you could go further than that: A(A(10)) is much bigger than A(1000), so you can get larger numbers faster by iterated applications of the Ackermann function. Turn the iteration into a function, and let B(n) be n applications of A to n. Iterated application of B would be even faster, so turn that iteration into a function: let C(n) be n applications of B to n.
But this process itself is iterative. So, define a new function: let iterA(n) be the nth level of iterated Ackermann functions applied to n, where iterA(1) is A(1), iterA(2) is B(2), iterA(3) is C(3), and so on.
Now, iterA can be applied iteratively. So, repeat again. The resulting function can be applied iteratively, so repeat again.
And this whole process of turning iteration into a function and then iterating that function is itself an iterative process, so it can be turned into a function...
Let A = {fastest published sequence}. # This is a macro for BB, Ackermann's, etc.
Iterate^Iterate^Iterate^Iterate^Iterate^Iterate^Iterate^Iterate^Iterate^Iterate^Iterate^Iterate^Iterate^Iterate^10(A, 10)