Let $\mathrm{a}_1, \mathrm{a}_2, \mathrm{a}_3, \ldots, \mathrm{a}_{100}$ be an arithmetic progression with $\mathrm{a}_1=3$ and $\mathrm{S}_{\mathrm{p}}=\sum_{\mathrm{i}=1}^{\mathrm{p}} \mathrm{a}_{\mathrm{i}}, 1 \leq \mathrm{p} \leq 100$. For any integer $n$ with $1 \leq n \leq 20$, let $m=5 n$. If $\frac{S_m}{S_n}$ does not depend on $n$, then $a_2$ is