Let's find the sequence associated to the sum:
[tex]\begin{gathered} a_n=a_1+(n-1)d \\ _{\text{ }}where\colon \\ a_1=11 \\ d=a_2-a_1=17-11=6 \\ so\colon \\ a_n=11+(n-1)(6) \\ a_n=11+6n-6 \\ a_n=6n+5 \end{gathered}[/tex]
Therefore, the sum will be given by:
[tex]\begin{gathered} \sum ^6_{i=1}a_n \\ \sum ^6_{i=1}6n+5 \end{gathered}[/tex]
