I know about Kneser, but if we take a simple recursion
$$^{1/d}b=c, a(0)=b, a(n)=b^{\frac{1}{^{d-1}(a(n-1))}}$$
so
$$\lim\limits_{n\to\infty}a(n)=c$$
and we can quickly find $c$ for positive integer $d>1$ and positive $b$. But $b$ has bounds, ex.
$$d=2, \left[(\frac{1}{e})^{\frac{1}{e}}; e^e\right]$$ $$d=3, [0; \approx2,421]$$ $$d=4, [\approx0,593; \approx1,904]$$ $$d=5, [0; \approx1,762]$$ $$d=6, [\approx0,543; \approx1,689]$$ $$d=7, [0; \approx1,632]$$ $$d=8, [\approx0,511; \approx1,592]$$
What is the law of those bounds? Why is lower bound for odd $d$ is $0$?