Answer
The sequence is arithmetic.
Common difference is $3$.
Work Step by Step
We compute the difference between each term and the preceding term. If the difference is same, then the sequence is arithmetic.
$a_{2}-a_{1}=17-14=3$
$a_{3}-a_{2}=20-17=3$
$a_{4}-a_{3}=23-20=3$
$a_{5}-a_{4}=26-23=3$
$a_{6}-a_{5}=29-26=3$
The common difference $d=3$ is constant and therefore the sequence is arithmetic.