Does $S_b$ become eventually greater than $S_{b+1}$? For a base $b \geq 2$, let $S_b$ be the sequence the $n$−th term of which is found by concatenating $n$ copies of the number $n$ written in base $b$, and then seeing the resulting string as a number in base $b$.
For example, given $b=2$, we get the sequence $1$, $1010_2$, $111111_2$, $100100100100_2$ etc, and for base ten we get $1$, $22$, $333$, $4444$, etc.
For fixed $b$, does the sequence $S_b$ become eventually greater than the sequence $S_{b+1}$? That is, does the $n$-th term of $S_b$ is greater than that of $S_{b+1}$ for all $n$ greater than some constant?

The proposition is false. Consider $S_2(n)$ and $S_3(n)$, where $n=3^k$, $ k\in\mathbb{N}.$
$ n = {1\underbrace{00\ldots 00}_{k \text{ zeros}} } (\text{ base } 3). $ This pattern ${1\underbrace{00\ldots 00}_{k \text{ zeros}} }$ repeated i.e. concatenated onto itself $\ 3^k$ times, $ \underbrace{100\ldots 00}_{1}\ \underbrace{100\ldots 00}_{2}\quad \ldots\quad \underbrace{100\ldots 00}_{3^k}\ $ in base $3$ is $\ > 3^{(k+1)3^k - 1}$.
On the other hand, $n=2^{k\log_2(3)\ }$ in base $2$ has at most $\ \left\lceil k \log_2(3) \right\rceil\ $ digits, and so $3^k$ in base $2$, repeated $3^k$ times - which has at most $\ 3^k\left\lceil k \log_2(3) \right\rceil\ $ digits - considered as a number in base 2, is:
$\ \leq 2^{\left\lceil k \log_2(3) \right\rceil\ \cdot3^k} \leq 2^{ (k \log_2(3) + 1) \cdot3^k } = 2^{ k3^k\left( 1 + \frac{1}{k\log_2(3)} \right) \log_2(3) } = 3^{ 3^k \left(k + \frac{1}{\log_2(3)}\right) },\ $ *which is $\leq  3^{3^k (k+1) - 1}\ $ for all $k\geq 1.\quad $
$*\quad$ The fact that $\ 3^k\left(k + \frac{1}{\log_2(3)}\right) \leq 3^k (k+1) - 1\ \forall\ k\geq 1\ $ is elementary: start by dividing both sides by $3^k$ and use the fact that $\ \frac{1}{\log_2(3)} \approx 0.63$.
