Read the Math Notes box in this lesson for information about an alternative notation for sequences, then use the given sequence to complete the parts below.

$a_1 = 5$
$a_n = a_{n − 1} + 6$

Therefore:     $\left. \begin{array} [t]{ l } { a _ { 1 } = 5 } \\ { a _ { 2 } = a _ { 1 } + 6 = 5 + 6 = 11 } \\ { a _ { 3 } = a _ { 2 } + 6 = 11 + 6 = 17 } \end{array} \right.$

Now continue the sequence:

1. $a_{4} = a_{?} + ? = ?$ 

   Hint (a):

   $a_{4} = a_{3} + 6 = ?$

   Answer (a):

   $\textit{a}_{4} \;=\;23$

2. $a_5 = a_? + ? = ?$ 

   Hint (b):

   See part (a).

3. The first $5$ terms of the sequence are:

   Hint (c):

   See parts (a) and (b).