How prove this limits $\lim_{n\to\infty}\frac{v_{5}(1^1\cdot 2^2\cdot 3^3\cdot 4^4\cdots\cdot n^n)}{n^2}=\frac{1}{8}$
Exploiting: $$\sum_{k=1}^{+\infty}\left\lfloor\frac{n}{5^k}\right\rfloor = \frac{n}{4}+O(1)$$ there is left very little to do.
Exploiting: $$\sum_{k=1}^{+\infty}\left\lfloor\frac{n}{5^k}\right\rfloor = \frac{n}{4}+O(1)$$ there is left very little to do.