[tex]\bf \begin{array}{ll}
term&value\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
a_1&8\\\\
a_2&6+a_{2-1}\\
&6+a_1\\
&6+8\\
&14\\\\
3&6+a_{3-1}\\
&6+a_2\\
&6+14\\
&20\\\\
a_4&6+a_{4-1}\\
&6+a_3\\
&6+20
\end{array}[/tex]
