6. Let $r, s, t$ be integers, and the set $\left\{a \mid a=2^{r}+2^{s}+2^{t}, 0 \leqslant t<s<r\right\}$ consists of numbers that form the sequence $\left\{a_{n}\right\}: 7,11,13,14, \cdots$, then $a_{36}=$ $\qquad$