13. Given the sequence $\left\{a_{n}\right\}$ with the sum of the first $n$ terms $S_{n}=3 n^{2}+5 n$, and in the geometric sequence $\left\{b_{n}\right\}$, $b_{1}=8$, $64 b_{n+1}-b_{n}=0$, and there exists a constant $c$, such that for any positive integer $n, a_{n+1}+\log c b_{n}$ is always a constant $m$, try to find the values of the constants $c$ and $m$.
13. Since $a_{n}=S_{n}-S_{n-1}=6 n+2\left(n \geqslant 1, n \in \mathbf{N}_{+}\right), b_{n}=8 \cdot\left(\frac{1}{64}\right)^{n-1}=8^{3-2 n}$, and $a_{n+1}+$ $\log _{c} b_{n}=6 n+8+(3-2 n) \log _{c} 8=2\left(3-\log _{c} 8\right) n+8+3 \log _{c} 8$, when and only when $3-\log _{c} 8=0$, then $c=$ 2, $a_{n+1}+\log _{x} b_{n}=17$ is a constant. Therefore, $m=17$.