grandes-ecoles 2024 Q19b

grandes-ecoles · France · polytechnique-maths-a__mp Number Theory Prime Counting and Distribution
Justify that $n! = \prod_{\substack{p \leqslant n \\ p \text{ prime}}} p^{\nu_{p}(n!)}$ and deduce that $$n \sum_{\substack{p \leqslant n \\ p \text{ prime}}} \frac{\ln(p)}{p} - n\ln(4) < \ln(n!) \leqslant n \sum_{\substack{p \leqslant n \\ p \text{ prime}}} \frac{\ln(p)}{p} + n \sum_{\substack{p \leqslant n \\ p \text{ prime}}} \frac{\ln(p)}{p(p-1)}.$$
Justify that $n! = \prod_{\substack{p \leqslant n \\ p \text{ prime}}} p^{\nu_{p}(n!)}$ and deduce that
$$n \sum_{\substack{p \leqslant n \\ p \text{ prime}}} \frac{\ln(p)}{p} - n\ln(4) < \ln(n!) \leqslant n \sum_{\substack{p \leqslant n \\ p \text{ prime}}} \frac{\ln(p)}{p} + n \sum_{\substack{p \leqslant n \\ p \text{ prime}}} \frac{\ln(p)}{p(p-1)}.$$