Not so much an question as adding another level to the same question as Ratio of logarithmic primes. (See answers, same as here.)
The Firoozbakht's conjecture (1982) is equal to:
$$(p_{n+1})^{n} < (p_n)^{n+1}.$$
Then the natural log is: $$n \ln(p_{n+1}) < (n+1)\ln(p_n).$$
Now, $$\ln(p_n) \leq \ln(n) + \ln(\ln(n)) + 1\text{, for $n \geq 2$. (*)}$$ With $n = n+1$ we have: $$\ln(p_{n+1}) \leq \ln(n+1) + \ln(\ln(n+1)) + 1, \text{for $n \geq 2$.}$$
And, because $$p_n \geq n*\ln(n)\text{, for $n \geq 2$; (**)}$$
the natural log of $p_n$ is: $$\ln(n) + \ln(\ln(n)) \leq \ln(p_n), \text{for $n \geq 2$}.$$
With $n = n+1$ we have: $$\ln(n+1) + \ln(\ln(n+1)) \leq \ln(p_{n+1}), \text{for $n \geq 2$}.$$
So, if $$n (\ln(n+1) + \ln(\ln(n+1))) < n \ln(p_{n+1}) < n(\ln(n+1) + \ln(\ln(n+1)) + 1) < (n+1)(\ln(n) + \ln(\ln(n))) < (n+1)\ln(p_n) < (n+1)(\ln(n) + \ln(\ln(n)) + 1)$$ holds then the conjecture is true for all terms. If only the outer terms only hold then the primes with largest gap maximal primes will hold true. Primes with smaller prime gaps require sharper bounds on the inner terms.
With the outer terms, dividing by $n(\ln(n) + \ln(\ln(n)))$ we have: $$\frac{\ln(n+1) + \ln(\ln(n+1))}{\ln(n) + \ln(\ln(n)) + 1} < \frac{n+1}{n} \text{, for $n \geq 2$}.$$
This inequality is true because the left-side increases slower than the right-side.
With the inner terms, dividing by $n(\ln(n) + \ln(\ln(n)))$ we have: $$\frac{\ln(n+1) + \ln(\ln(n+1)) + 1}{\ln(n) + \ln(\ln(n))} < \frac{n+1}{n} \text{, for $n \geq 2$}.$$
This inequality is false for every $n$ value tested.
Is there a problem with any of these statements?
References:
$(*)$ Proved in Dusart 2010, ESTIMATES OF SOME FUNCTIONS OVER PRIMES WITHOUT R.H.,section 4. Useful Bounds)
$(**)$ Used in Dusart 1999, THE k th PRIME IS GREATER THAN k(ln k + ln ln k − 1) FOR k ≥ 2 Lemma 1. p. 413
This approach will not work since Dusart's bounds are not strong enough to prove that inequality. His bounds have error $n/\log^k n$ but you need closer to $\log^2 n$ to be able to prove Firoozbakht's conjecture.
It's easy to see that your inequality will fail for large $n$. Multiply by $n\log n+n\log\log n$ (which is positive in this range) to get $$ n\log(n+1)+n\log(\log(n+1))+n\stackrel{?}{<}n\log n+n\log\log n+\log n+\log\log n $$ which is $$ n<n(\log(n+1)-\log n)+n(\log(\log(n+1))-\log\log n)+n\stackrel{?}{<}\log n+\log\log n $$ but clearly $\log n+\log\log n<n$ for large $n$.
As an aside, work by Maier, Granville, and others since Firoozbakht made her conjecture has shown that Firoozbakht's conjecture is likely false, though the first counterexample is probably very large.