Kevin Wampler <wam### [at] uwashingtonedu> wrote:
> nor is #4, as I don't think it's possible).

  AFAIK the simplest recursive solution to the problem is (as I mentioned in
another post) this:

f(0) = 0
f(n) = floor(n/5) + f(floor(n/5))

  One could try to prove that the above cannot be expressed in closed form.
But AFAIK that wouldn't be a proof that there is no closed form solution at
all, just that the above method cannot be expressed in that form.

  Of course for a simpler version of the problem one could remove the
limitation that the solution must not be recursive. It's, in fact, not
completely trivial to come up with the simplest possible solution, as above.

-- 
                                                          - Warp

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