ThmDex – An index of mathematical definitions, results, and conjectures.
Weak Stirling formula
Formulation 0
Then \begin{equation} n \log n \overset{n \to \infty}{\sim} \log n! \end{equation}
Formulation 1
Then \begin{equation} \lim_{n \to \infty, \, n > 1} \frac{n \log n}{\log n !} = 1 \end{equation}
Proofs
Proof 0
Let $n \in 2, 3, 4, \ldots$ be a positive integer. Using the results
(i) R4899:
(ii) R4898:

we have the inequalities \begin{equation} n \log n - n < \log n! < n \log n \end{equation} Dividing each side by the nonzero quantity $n \log n$, we obtain \begin{equation} 1 - \frac{1}{\log n} < \frac{\log n!}{n \log n} < 1 \end{equation} Since $\log n \nearrow \infty$ as $n \to \infty$, then $1 - \frac{1}{\log n} \nearrow 1$ as $n \to \infty$. Thus, by the squeeze principle, we have \begin{equation} \lim_{n \to \infty} \frac{\log n!}{n \log n} = 1 \end{equation} which is what was desired to be shown. $\square$