2. Let the sum of the first 4 terms of an arithmetic sequence be 26, the sum of the last 4 terms be 110, and the sum of all terms be 187. This sequence has $\qquad$ terms.
\begin{array}{l}\text { 2. } n=11 . \\ \quad a_{1}+a_{2}+a_{3}+a_{4}=4 a_{1}+6 d=26, a_{n}+a_{n-1}+a_{n-2}+a_{n-3}=4 a_{n}-6 d=100, S_{n}= \\ \frac{n}{2}\left(a_{1}+a_{n}\right), a_{1}+a_{n}=34 \text {, so } \frac{n}{2} \cdot 34=187 \text {, i.e., } n=11 .\end{array}